Ancient Greece and Rome 1200 BCE-476 CE: Philosophy

Arts and Humanities Through the Eras. Editor: Edward I Bleiberg, et al. Volume 2. Detroit: Gale, 2005.

Beginnings of Greek Philosophy


Greek philosophy began in a city-state on the coast of south-west Turkey: Miletus, which claimed that it was founded by a city on Crete called Milatos—probably Mallia on the north coast of Crete—in the Minoan period. If so, the Minoan foundation did not survive the catastrophe that overtook the Bronze Age civilization about 1200 B.C.E., and Miletus was refounded by Ionian Greeks during the age of migrations in the eleventh century B.C.E. The city prospered, and civic life was as turbulent as it was in most city-states in the Early Archaic Period of the seventh and early sixth centuries B.C.E.Around 600 B.C.E., Miletus’ independence was threatened by her neighbor, the Lydian Empire. The city of Lydia was ruled by a strongman—a “tyrant” as the Greeks called such men—named Thrasybulus, and he led the resistance to Alyattes, king of Lydia, who harried the Milesians for eleven years. In the end Alyattes made peace and alliance with them but soon had to turn his attention to his eastern frontier where he faced the aggressive empire of the Medes who had destroyed the Assyrian Empire with some help from Babylon and were now expanding into Asia Minor. In 585 or 584 B.C.E., the Lydian and Median armies met at the frontier of Lydia, the Halys River which flows into the Black Sea. Just as they were on the verge of battle, there was an eclipse of the sun. A young man from Miletus, Thales, who was there among the Milesian allies supporting Alyattes, was said to have foretold the eclipse. Modern scholars find this story hard to believe, but it is clear that this man would be the founder of Greek natural philosophy—that is, speculation about nature and the natural causes of what occurs in the cosmos.

Thales, Anaximander, and Anaximenes

Thales believed that everything in the world is made of matter which might take various forms, be it solid, liquid or gas. The one matter that he knew could appear in all these forms was water. If heat was applied to ice, it became water, and heat applied to water produced steam that in turn could condense and return to water. Thales’ disciple Anaximander carried Thales’ speculation a step further. He suggested that the substance underlying all natural phenomena was not water but rather something that he called the apeiron—the “Infinite” (or “Indefinite”)—matter that had no boundary. He argued that the world was a cylinder with a flat top that provided men with living space. It floated freely in space, equally distant from all things, and thus without any need of support. Anaximander’s thoughts were daring and almost modern, but his follower Anaximenes abandoned his concept of the apeiron and suggested instead that the primary substance of the universe was aer—the Greek word for “air.” It is clear that Anaximenes’ aer is more than mere “air,” however. Rather, it is a kind of mist out of which denser substances are formed by condensation, much as felt can be made from wool by the process of felting. For Anaximenes, aer was a material substance. Unlike the apeiron of Anaximander, it could be defined, and later natural philosophers who argued that the universe was constructed of matter looked back on Anaximenes as the last great thinker of the Milesian School who brought the speculation that Thales began to its natural conclusion.

Pythagoras and the Pythagoreans

The Life of Pythagoras

Pythagoras, perhaps best known for his theorem on triangle angles and lengths, left behind him a great reputation as not only a mathematician, but also as a philosopher and cult figure. Yet he is an indistinct personality, veiled in the shadows of legends that grew up around him. He was born on the island of Samos off the coast of modern Turkey in the first half of the sixth century B.C.E. and he was the son of an engraver of gemstones. In 532 B.C.E. a Samian named Polycrates seized control of the government of Samos and established himself as a tyrant. Polycrates maintained a splendid court and ruled like a pirate king, living on the fringe of the Persian Empire which would eventually, around 517 B.C.E., overthrow him, but during his heyday no cargo ship in the southern Aegean Sea was safe from his marauding warships. Pythagoras, it is reported, left Samos to escape Polycrates’ dissolute court, and emigrated to southern Italy, to the Greek city of Croton, modern Crotone. The Greeks had founded a number of colonies in the region: not only Croton, but also Sybaris, Locri, Metapontum, and Rhegium. These colonies battled each other for the rich farmland of the area; when Pythagoras reached Croton, it had just suffered a defeat at the hands of its smaller neighbor, Locri. The rich Crotoniates, humiliated by their defeat, were ready for Pythagoras’ austere teachings. He gathered about him a brotherhood of Pythagoreans who were both scientists and mystics with secret doctrines and curious taboos; Pythagoreans wore white clothes to worship the gods and avoided eating beans, to name only two of the taboos that governed their lives. The Pythagorean circle soon dominated the aristocratic ruling class in Croton. The Pythagorean brotherhood became a force in the politics of the Greek cities in southern Italy until there was a violent reaction against their high-handed oligarchic rule that aroused strong resentment. Pythagoreans were massacred, and Pythagoras himself had to flee. He went to neighboring Metapontum where he died in exile. Pythagoreans remained active in southern Italy, continuing their scientific inquiries. It was a Pythagorean in the first half of the fourth century B.C.E., Archytas of Tarentum, who was recognized in the Greek world as the founder of mechanics, the branch of physics that deals with motion.

The Religious Teachings of Pythagoras

Pythagoras introduced a new vision of the fate of human beings after death: the doctrine of metempsychosis, or the transmigration of the soul from one body to another. The traditional religion of the Greeks which is reflected in the Iliad and Odyssey of Homer taught that humans differed from the gods in that human life was short, whereas the gods never died. Pythagoras taught that the soul was reborn after death and went through a cycle of rebirths until it attained the immortality that hitherto only the gods enjoyed. The details of Pythagoras’ original doctrine cannot be recovered now, for later philosophers added their own insights. The question of whether there was a set number of rebirths that the soul had to experience before it reached a blessed state was answered by the poet Pindar, for instance, who wrote that if a soul avoided injustice for three lives, it would attain a marvelous existence in the Isles of the Blessed. Philosophers differed on whether the transmigrating soul was the same soul that governed a person’s sentience and activity during his lifetime; Plato thought it was, but the philosopher Empedocles thought that it was not the psyche (soul) that transmigrated but the daimon (spirit). The doctrine of transmigration that Pythagoras taught his followers pioneered a new field of speculation about life after death. Not everyone was impressed. Pythagoras’ contemporary, the poet and philosopher Xenophanes, mocked the doctrine with a story in which Pythagoras urges a man to stop beating his dog, recognizing in the dog’s yelps of pain the soul of a dead friend.

The Cosmology of Pythagoras

Pythagoras’ theory of the nature of the universe—his cosmology—was influenced by the Milesian philosophers, Anaximander and Anaximenes. Anaximander’s “Infinite” and Anaximenes’ “Limitless Air” corresponded to what Pythagoras called the “Dark,” which is cold, dense, without light, and without boundaries. Yet “Light” also exists, the opposite of the limitless “Dark,” and it has form and thus it has limits, for without limits, matter is by definition formless. Portions of the limitless “Dark” are attracted to the “Light” where they receive form and limit. The Pythagoreans conceived of the “Light” as a living, breathing thing, and from the portions of the “Dark” which “Light” breathes in, the celestial bodies are formed. The celestial bodies numbered ten, and they revolved from east to west around a central fire. The sun reflects light from the central fire and thus provides Earth with light and warmth. Thus the cosmos consists of the central fire, Earth, the moon, the sun, Mercury, Venus, Mars, Jupiter, Saturn, and counter-earth which seems to serve no other purpose than to make the number of heavenly bodies total ten, which the Pythagoreans considered a sacred number. At the very limit of the cosmos were the fixed stars. Except for these fixed stars, the heavenly bodies moved around the central fire, and since moving objects can produce sound, Pythagoras assumed that harmonia existed in the universe. Harmonia was the word for the octave-system of music he developed according to mathematical ratios. Hence, arose the Pythagorean theory of the “music of the spheres,” though it is not at all certain that Pythagoras himself thought of the heavenly bodies as spheres.

The Neopythagoreans

Pythagoras came to be regarded as the archetypal philosopher by the end of the fourth century B.C.E., and the followers of Plato and Aristotle absorbed many of his ideas. But his reputation was such that there appeared forged documents attributed to him from the third century B.C.E. onwards, and their numbers grew in the first century B.C.E. when a sect which modern scholars call the “Neopythagoreans” was founded. Neopythagorean doctrine owes more to Plato than Pythagoras. The Neopythagoreans built up a cult around Pythagoras so that he became a legendary semi-divine sage whom the pagans in the Christian era put forward as a rival for Christ. It is not always easy to separate the Neopythagorean sage from the semi-legendary but nonetheless historical figure of Pythagoras.

Xenophanes, Heraclitus, and Parmenides

Xenophanes of Colophon

Xenophanes was one of the first philosophers to promote monotheism in Greece, and was the founder of Eleatic philosophy—the belief that above everything in the world there is an unchanging, everlasting “One.” He did not define this “One” in his own writings, but many of his later followers, such as Plato and Aristotle, would attempt to steer this concept towards a belief in one God, contrary to the Greek belief of many different gods. Xenophanes was a native of Colophon, a city on the western fringe of Asia Minor, which he left when it was conquered by Persia about 546 B.C.E. He would spend the rest of his life traveling the Greek world. He had a close connection with Elea, modern Velia in southwest Italy, which was founded by Ionian Greeks fleeing the Persian conquest. Xenophanes was an accomplished writer whose influence was immense in the intellectual world of the western Greeks, among the Greek cities in Sicily and southern Italy. He criticized Homer and Hesiod for their portrayal of the gods. They were wrong, Xenophanes asserted, to show the gods in human form with human faults, though it was natural to do so; oxen and lions, if they had hands, would draw their gods as oxen and lions. Xenophanes taught instead that there was a single supreme divine being who, without moving, controlled the universe through his intellect. Xenophanes had a gift for observation that not all Greek intellectuals shared. He found seashells and fossilized sea-creatures in rocks and inferred that there was once a time when the sea covered the land, and hence the earth must have been subject to periods of flooding and drying out. He may even have written a treatise on the subject.

The Eternal Fire of Heraclitus

Heraclitus of Ephesus was inspired by Xenophanes’ idea of an everlasting unchanging “One,” but like many philosophers of his time did not think this “One” was a being or a person, but was instead a basic material that was transformed in some way into other kinds of material. Thales of Miletus had pinpointed water as that basic material and Anaximenes had thought it was air; Heraclitus chose fire. Fire, he claimed, was an infinite mass which was eternal—no divine power created it—and it was kindled and extinguished according to fixed measures. The kindling and quenching of fire maintained the world order. Heraclitus came to this conclusion after observing how flames, flickering in constant motion, transformed wood into ashes and smoke, and yet the fire maintained its own identity as fire. Once it was quenched, it could be rekindled. Like fire, Heraclitus’ universe was subject to constant change. Everything was in constant motion. One famous saying of Heraclitus was that a person cannot step twice into the same river, for new water is constantly being carried past him by the flow of the stream, and hence the river is never entirely the same from one minute to the next. Yet, like fire, the river itself continues to exist.

The Unity of Opposites

Heraclitus’ teachings were notoriously obscure, but he was identified in the ancient world with a number of doctrines. One doctrine maintained that the world was in a state of continual flux; his saying, “Everything flows,” made the universe akin to a moving stream. He also believed in the unity of opposites: things that seem to be opposites are actually aspects of the same thing. This unity is demonstrated in the seeming opposites of “heat” and “cold” which are interdependent: “cold” is the absence of “heat.” Once the continual flux that never ceases in the world removes “heat,” we have “cold.” “What is cool becomes warm and what is warm becomes cool,” Heraclitus wrote. So the young and the old are aspects of the same, and so are the living and the dead, for the one becomes the other. One of Heraclitus’ axioms reads, “The road up and the road down are the same”—meaning there is a single road with two-way traffic. It is the tension between opposites that allows living things to exist, just as the string of a lyre will sound the correct note when it is placed under the right degree of tension by drawing it in opposite directions. This interaction of opposites, which Heraclitus identified as strife, is a creative force, and this belief probably explains one strange assertion of his: “War is the father of all and king of all.” Everything is created and passes away through strife between opposing forces. The world is a mass of conflicting tensions but, at the same time, these contrary forces are bound together by a strict unity. The strife between them results in a sort of balance which Heraclitus identified as justice, and justice maintains order—hence Heraclitus asserted that the sun would keep its allotted course in the heavens, for otherwise the Furies, the agents of Justice, would punish it. The unity of opposites is the central feature of the logos that Heraclitus proclaimed.

The Logos

Many of Heraclitus’s views on the logos are attributed to his study of Xenophanes. Logos is a word with many meanings. It means “word”—not “word” in the strictly grammatical sense, but rather “word” as a vehicle expressing thought, and so it comes to mean the thought itself. It is the wisdom of the mind expressed in speech. For Heraclitus, the word logosseems to have expressed the Intelligence that directs the manifold changes in the world. It was both willing and unwilling to be called Zeus, according to one of Heraclitus’ cryptic utterances. The logos that Heraclitus proclaimed would continue to haunt philosophy and theology as well. In the early Christian era, some thinkers considered Heraclitus a Christian before his time because of his emphasis on logos, a Christian synonym for Jesus Christ derived from the opening verse of the Gospel of St. John: “In the Beginning was the Logos (the Word) and the Logos was with God and the Logos was God.” In the Roman period, the Stoic philosophers embraced Heraclitus because his doctrine of eternal fire that was alternatively kindled and quenched seemed to fit their belief that the world passed through cycles, each of which ended in fiery destruction. Yet Heraclitus was neither a proto-Stoic nor a proto-Christian, though his eccentric lifestyle and his oracular utterances mark him out as almost as much a religious teacher as a natural scientist.

Parmenides of Elea

While Xenophanes and Heraclitus furthered the idea of the everlasting element that underrides all things, it was Parmenides, born in Elea about 515 B.C.E., who brought the line of speculation that began with Thales and Anaximander to its logical conclusion. All the Ionian philosophers who speculated about nature took for granted that there was a primary substance such as water, air, or fire that could take different forms. They left no place for nothingness. The Greeks had no symbol for “zero.” “Nothing” was something that could not be defined or expressed; the opposite of “that which exists” is “that which does not exist.” Parmenides pointed out the consequences of this line of thought. In the first place, “that which exists” cannot have been created for if it were, it would have to be created out of either something or nothing. Nothing does not exist and so “that which exists” cannot not have been created out of it. Nor can it have been created out of something, for the only “something” is “that which exists.” Nor can anything else besides “what exists” be created, for there is no empty space where such creation could take place. Parmenides refuted all accounts of creation with a simple principle that could not be contradicted: “Out of nothing there is nothing created.”

The Universe of Parmenides

Thus for Parmenides “that which exists” is matter that is continuous and indivisible, and therefore the universe must be a continuous, indivisible plenum, that is, a space filled with matter. The plenum cannot move, for if it did, it would have to move into empty space—a vacuum, the opposite of a plenum—and empty space is “nothingness,” which does not exist. The plenum must be finite, with definite boundaries, and spherical, for matter cannot have direction, and that can be true only in a sphere. Within the plenum there can be no movement, for if an object moves, then there must be some empty space into which it can move, and there is no empty space. So the evidence of our eyes that tells us that things in the world that we see do move must be an illusion. The messages that our senses send to our brain about the nature of the world must be wrong. The alternative would be to believe that the underlying assumption of all the philosophers from Thales to Heraclitus—that the world of the senses was made from some basic matter such as water, air, or even the “boundless” of Anaximander—had to be wrong.

Zeno’s Riddles

Zeno, born around 495 B.C.E. was a favorite of Parmenides, and he made it his business to drive home the logical conclusion of the Eleatic school of philosophy that motion was a mere illusion. The paradoxes by which he drove home the logic of the Eleatics were famous. One was the paradox of the arrow that is shot from a bow. The arrow must either be moving in the place where it is or where it is not, and it cannot be moving in the place where it is, or it would not be there. Nor can it be moving in a place where it is not, for it is not there. Therefore the moving arrow is stationary. To put it another way, the apparent motion of the arrow is like a moving picture, which is actually a succession of still pictures that are fed rapidly through a projector and produce the illusion of motion. In fact, at every point in its trajectory, the arrow is actually at rest and what is at rest at every point is not moving. Zeno used this deduction as proof that Parmenides was right: there is no motion. The Greek philosophers had no solution to this paradox, and the modern world had to wait until Sir Isaac Newton discovered differential calculus before Zeno’s error could be discovered. Another famous paradox proposed by Zeno was that of Achilles, a legendary Greek hero, and the Tortoise. Achilles and a tortoise run a race, and the tortoise has a head start. Achilles cannot overtake the tortoise, for when he reaches the point where the tortoise started, it has already moved on to further point, and when Achilles reaches that point, the tortoise has already moved further on, and so on through an infinite series which has no end. There is no final term to this infinite series and so Achilles can never pass through the final term. Yet here, Zeno’s logic ultimately proved itself faulty, for it is a fair question to ask why, if there is no final term, does Achilles need to pass through it? It cannot be necessary for Achilles to pass through a non-existent final term to overtake the tortoise. Yet the relentless logic of the Eleatic philosophers was hard to counter.

Melissus of Samos

One of the major flaws in the universe of Parmenides was the idea of a plenum with a finite boundary. If there was nothing whatsoever beyond the boundary, what happened if a person went to the outer edge of the universe, kicked a hole through its skin, and thrust his foot into nothingness, which does not exist? Melissus of Samos, who lived in the mid-fifth century B.C.E. and was the last member of the Eleatic School, attempted an answer. He defended the basic doctrine of the Eleatics, but proposed a plenum without a finite boundary, so that the universe was infinite. So no one could kick a hole through the boundary of the universe, for there was no boundary. Yet there was still no place for movement. Melissus had to deny that the senses could yield us true knowledge, for the intelligence that our eyes report to our brains indicates that there are bodies in motion in the world about us. The Eleatics denied real existence to the “phenomena”—that is, to the objects that appear to us as actual—and any thinker who wanted to save the phenomena had to devise an argument that countered their uncompromising logic.

Empedocles, Anaxagoras, and the Atomists

The Idea of Four Elements

Empedocles attempted to find an escape from the logical conclusions of the Eleatic philosophers. Born in the early fifth century B.C.E. in Sicily, Empedocles took on many roles before becoming a philosopher. For a short time he was a politician, and then he turned his attention to educating people on the topics of medicine and religion. When he embarked on his own study of philosophy, he held two very important views. First, he abandoned the accepted belief that all philosophers had held since Thales: that all matter was derived from a single underlying substance. Instead he theorized that the world, as it is known, is due to the mixing and separation of four elements: earth, air, fire, and water, which Empedocles called “roots.” Second, he accounted for the blending and the separation of the elements by theorizing the existence of two different forces that blend and separate called Love and Strife—attraction and repulsion. The first caused the elements to blend together and created the physical world, whereas Strife forced the elements apart and caused destruction.

Love and Strife

Empedocles compared the blending of the elements to what a painter does when he mixes his basic colors: by combining his colors, he produces new tints. So in the universe, which Empedocles, like Parmenides, imagined as a sphere, the elements are mixed together by the attractive force of Love in their proper ratios to form concrete objects; human bones, for instance, were two parts water, four parts fire, and two parts earth. This blending of the elements results in genesis and growth in the world of the senses, whereas the separation of the elements results in death, destruction, and decay. Strife is on the outside of the sphere but in due time it penetrates it, driving Love towards the center of the sphere. Gradually the four elements separate from each other. Death and decay occurs. Then the opposite process begins: Love, which has been driven into the center of the sphere, begins to expand, driving out Strife. This never-ending cycle is like the flux and reflux of blood from the heart, or the action of breathing air into the lungs and then expelling it. All the objects that can be seen are unstable compounds. Blending the elements brings about genesis and the creation of new things, and the dissolution of the mixture of elements brings about their decay.

The Problem of Motion

Empedocles still had to explain how this blending of the elements took place. The process implies movement, and Empedocles accepted Parmenides’ concept of a sphere as a plenum in which there was no movement for lack of space in which to move. Empedocles explained that there were “pores” in the elements that allowed them to move together and coalesce. The Greek for “pores” is poroi, passageways, like the holes in a sponge. These “pores” provided passageways so that the elements could move into each other and create unstable compounds, and then move apart and destroy them as the endless cycle of cosmic change.

Anaxagoras of Clazomenae

Anaxagoras, a contemporary of Empedocles, took up Empedocles’ theory of blending elements and completed it by describing what caused motion in these elements. Anaxagoras, born in Clazomenae in the early fifth century B.C.E., was a man of privilege from a wealthy background. He gave up a good deal of his possessions and lands to study science and philosophy, to the point that he left Clazomenae after 470 B.C.E. and settled in Athens. He stayed there for some forty years until he was driven into exile on a charge of impiety. Much like Empedocles, Anaxagoras asserted that the Greeks were wrong to speak of genesis and destruction; instead they should call genesis a “blending together,” and destruction “decomposition.” Empedocles spoke of “elements” whereas Anaxagoras spoke of “seeds.” His “seeds,” however, were not the same as Empedocles’ “roots.” Rather, they were themselves compounds, each with a fixed shape, color, and taste, and each containing a fixed number of dynameis—the word means “powers” or “capabilities.” The ration of dynameiswithin each seed is a fixed amount, and they tend to exist in pair of opposites, such as hot dynameis coupled with cold ones, heavy with light ones, and moist with dry ones. A stone is made up of seeds with more heavy dynameis than light ones and more dry than moist ones—hence its solidity. Every seed has a portion of everything within it, no matter how minutely it may be divided.

The Power of “Mind”

Anaxagoras realized that his theory of “seeds” was incomplete. He still needed a source of motion that allowed this blending and uncoupling of the “seeds.” Anaxagoras, however went a step beyond Empedocles and created a force called the Nous (Mind), which served as the source of knowledge for the human intelligence. It was not an incorporeal force, however, but a kind of unmixed fluid that did not have portions of other things in it. It coupled the “seeds” and uncoupled them by setting them in rotation. That is, “Mind” established a kind of vortex which began in the center of the “seed” and then spread further and further, evidently somewhat like the ripples that a stone thrown into a tranquil lake produces on the surface of the water. Anaxagoras did not expand further on his concept of the Nous, and this left future philosophers dissatisfied with the theory. Although initially attracted to Anaxagoras’ philosophy in his youth, Socrates complained that Anaxagoras thought of “Mind” simply as a mechanical device to get motion started in his universe, and once that was done, he had no further use for it.

The Atomic Theory

Escaping the Logic of the Eleatic School

Both Empedocles and Anaxagoras attempted to evade the ruthless logic of Parmenides and the Eleatic School of philosophers who argued that there are two opposites, “that which exists,” which is matter, and “that which does not exist,” which obviously does not exist. Since the world is composed of matter which does exist, it fills all the available space. Thus there can be no motion, for motion implies that there is empty space into which an object in motion can move, and there is no empty space. Parmenides’ follower, Zeno, proved to his own satisfaction that an arrow in flight only appears to move. In actuality, at any given point in its apparent flight, it is at rest. To escape from this logic, someone had to produce a theory to prove that empty space was not the same thing as the Eleatic’s “that which does not exist.” The philosopher who provided the necessary leap of imagination to get over this Eleatic idea was Leucippus of Miletus, the same city that fathered Thales, Anaximander, and Anaximenes who had started the long tradition of Greek speculation about the nature of the universe. Unlike his predecessors, he is a shadowy figure, overshadowed by his more famous follower Democritus to such an extent that some Greeks even denied his existence. He was recognized, however, by such philosopher greats as Aristotle, who headed the school known as the Lyceum in Athens of the fourth century B.C.E., and his successor Theophrastus. Both men referred to Leucippus as the author of a work on the atomic theory titled the Great World System, although other philosophers—notably Epicurus (342-271 B.C.E.) and his followers—attributed this theory to Leucippus’ pupil, Democritus of Abdera. Although Democritus was a prolific writer, none of his works survive to the present day.

The Atoms of Leucippus and Democritus

Leucippus and Democritus conceived of particles of matter called “atoms” which moved through space like the flecks of dust that can be seen moving in a sunbeam. Some were large, some small, and some might be smooth and round and others might have an irregular shape. The atoms moved through void. Parmenides had argued that the universe was a plenum filled with matter, and there was nothing else, but Leucippus and Democritus argued that the opposite of a plenum—a vacuum—also existed. Each atom, however, which was so small as to be invisible, was itself a plenum, and could not be split. Atoms were atoma somata (bodies that cannot be divided). The atoms were perpetually spinning, like the “seeds” of Anaxagoras, and as they collided some stuck together while others were forced apart. Small, perfect atoms gravitated towards the outside of the universe and formed the dome of the sky, whereas heavier atoms gravitated towards the center and formed earth. The concept of weight and its opposite, lightness, was something the Greeks did not understand, for the force of gravity had not yet been defined. Leucippus explained that weight resulted from the size of the atoms and their combinations, but neither he nor Democritus seemed to have thought weight very important and they never committed the error that Aristotle made later, of arguing for the existence of absolute weight. Epicurus later assigned different weights to the atoms, and argued that the heavier atoms moved at a different speed than the lighter ones. For Leucippus and Democritus, weight was a relative thing and the atoms moved at random. But they collided, and from their collisions they formed the groups of atoms that make up every object in this world, including human beings. The atomists saw an analogy in the letters of the alphabet. Each letter is a separate symbol with its own form, but when arranged together in various ways they form words. So the various arrangements of the atoms form different objects in the same way as the different arrangements of letters make different words. It was taken for granted that the atoms would always keep moving unless something intervened to make them stop.

The Problem of the Soul

The atomic theory of Leucippus and Democritus assumed that the soul, too, was made up of atoms and void. Soul atoms were round and very mobile, and the atomists argued that there was also a fiery quality about them. Fire-atoms exist in the universe, but had no influence on how material things move; men breathed them into their bodies, at which point they formed an aggregate of fiery atoms known as the soul, and on death, it dissolved. This theory hearkened back to the old Greek belief that the soul—the psyche—was the breath of life which departed from the body at death. According to the atomic theory, the soul that is composed of atoms leaves the body when the last breath is drawn and returns to mingle with the fire-atoms of the universe. There is no place in this theory for any belief in the immortality of the soul. Yet the soul that is within every living person endows him with his intellect and his senses and even governs the motion of his limbs. The senses allow humans to see, hear, and taste, for objects project images of themselves as emanations, and these are received by the soul. Animals apparently did not have souls of this sort, though they, too, breathed in air and exhaled it, and in fact, the concept of the soul according to the atomic theory seems to involve a good deal of inconsistency.

Democritus the Moralist

Democritus wrote on a remarkable number of subjects, including mathematics, and among them was a theory of ethics which he fitted to his atomic philosophy. One treatise titled On Cheerfulness began with a warning against restless activity. Freedom from disturbance, he wrote, is what brings about human happiness. Cheerfulness is the ultimate good and it is a state in which the soul lives tranquilly, without being disturbed by any fear or superstition. Here we find a new conception of life for a person, not as a part of a social order such as a city, but rather as an individual. Human happiness was the sum total of all feelings that give pleasure—not just vulgar pleasures, though Democritus did not rule them out, but also pleasures in the beautiful. His thoughts about the gods are difficult to discern; one surviving fragment of his writings refers to them as providers to mankind of all that is good, and another fragment mentions them as images that approach human beings to impart knowledge of the future and of the divine. On morals, he was no relativist. As far as he was concerned, there was one standard of morality for everyone:

The same things are good and true for all mankind, but some men take delight in some things and others in others.

The Sophists

A Shift in Emphasis

The scientific philosophers, from Thales to Democritus, had done their best to understand the nature of the world with remarkable achievement. The intuition of Leucippus and Democritus—that the universe was created of atoms and void—was a remarkable one, but the Greeks lacked the scientific equipment to make it anything more than an hypothesis. In the classical period (480-323 B.C.E.), philosophy sought new areas of speculation. In Athens, Socrates was a pivotal figure, so much so that the natural philosophers, from Thales to Democritus, are lumped together under the label, “Presocratics.” Yet the way for Socrates was prepared by a group of thinkers and teachers called Sophists. The Greek wordsophistes, from which the word “sophist” is derived, means a “master of one’s craft,” and it has a secondary meaning of “one who is expert in practical wisdom.” Experts in classical Greece always suffered from a degree of prejudice—the American slang word “egghead” is a good translation of sophistes. But it was not until the fourth century B.C.E. that the word “sophist” carried distinct overtones of disdain, and Socrates’ disciple, the philosopher Plato, must bear much of the responsibility for that development. Plato was at pains to show that Socrates was not a Sophist, though some of his contemporaries clearly thought that he was. Socrates had disciples, but Plato claimed that he never charged tuition fees whereas the Sophists did.

The Demand for Higher Education

The Sophists appeared at a time when the old aristocratic prejudices of archaic Greece were breaking down all over the Greek world. The age of the Sophists seems to have begun outside Athens, and it gave rise to a cadre of international experts who, like the lyric poets in archaic Greece, roved from city to city in search of students willing to pay the tuition fees they charged. In the aristocratic thought-world of archaic Greece, arete, a word which combines the meanings of “virtue” and “valor,” was an innate quality. So far as there was an educational program, it consisted of poetry—particularly the poems of Homer—music, training in arms, and following the examples of one’s elders. This sort of education was incomplete in classical Greece, however, where individuals needed to be skilled in presenting cases in court; in the public assemblies, competence in public speaking paid dividends. The Sophists claimed to be able to teach the skills necessary for success. They asserted that they could make their disciples proficient in rhetoric and the verbal skills to make a weak case appear stronger than it really was. From teaching men how to be good at something like rhetoric, the claim to teach men goodness itself required no great leap of the imagination. One of the learned men who approached these broader questions was Protagoras, the first Sophist to charge tuition fees, who came from Abdera in northern Greece not far from the border with modern Turkey. He was an itinerant teacher who spent most of his life traveling; he visited Sicily and he came to Athens at least twice. During one of these times in Athens he was threatened by a conservative Athenian named Pythodorus with a charge of impiety, and he made a timely departure. His books were publicly burned, but Protagoras’ reputation outside Athens no doubt resulted in the survival of copies of his books elsewhere in the Greek world.

The Teachings of Protagoras

Conservative pious Athenians had good reason to be shocked by Protagoras’ books, which he presented during public readings. An early work titled On the Gods, which was his first book to be read in public, began with the memorable sentence:

Of the gods, I can know nothing, neither that they are nor that they are not, nor how they are shaped if at all. Many things prevent such knowledge—the uncertainty of the question and the shortness of human life.

With these few words, Protagoras turned his back on the gods to whom the Greeks sacrificed all over the Greek world, though it cannot be said for certain that he was an out-and-out atheist. His outline for the proper education of a politician was laid out in a book titled Truth, or Refutations which began with a sentence that became famous as the summary of his philosophy:

Man [or “a man”] is the measure of all things, of things that are, that they are, and of things that are not, that they are not.

In the context of its time, this passage may have been a protest against the Eleatic school of philosophy, particularly Parmenides, who argued that existence as men perceive it is not at all what it actually is. Protagoras’ rejoinder to the Eleatics was that as things exist for me, that is what they are for me, and as they exist for you, that is what they are for you. In other words, each person has a right to trust his own senses. Yet there is little doubt that Protagoras carried over this relativist view into judgments of value as well. The inference was that there was no such thing as absolute justice or absolute goodness; rather they were matters of personal judgment. Thus Protagoras held that one could argue equally well for or against any proposition; whether or not the proposition had some merit was of no consequence since all opinions were equally true. Some opinions, however, could be better than others even if they were not more true; that, at least, is what Plato suggested in his dialogue, the Theaetetus, as Protagoras’ meaning, and it is very close to that of a modern pragmatist.

Gorgias of Leontini

Like Protagoras, Gorgias of Leontini found the conclusions of the Eleatic philosophers impossible to accept. But unlike Protagoras, whose reaction was to affirm that it was right for every person to decide for himself what was true, Gorgias maintained that there was no truth at all. Gorgias was from the Sicilian city of Leontini and he came to Athens in 427 B.C.E. as an envoy for his native city. His skill at public speaking made a great impression on the Athenian public. He introduced Athens to methods of persuasion that had been developed in Sicily, and his influence on Athenian literature and prose style was enormous. During his time in Athens he studied and presented his own brand of philosophy. One of his works On Nature, or What Does Not Exist, attempted to show that there is nothing; even if there is something, we cannot know it, and even if we could know it, we cannot communicate our knowledge to anyone else. This sort of nihilism would seem to lead to the conclusion that there is no right or wrong, but Gorgias did not go so far. Others did, however; in the first book of Plato’s Republic, an Athenian named Thrasymachus maintains that there is no “Right” at all, and what we call “Right” is only what is advantageous for the more powerful person who can force weaker persons to accept it as lawful and binding simply because he is more powerful. Thrasymachus was a teacher of rhetoric in Athens when Gorgias visited Athens, and though the Republic of Plato was written more than a generation later, Plato probably reported accurately the conclusions that some of Gorgias’ disciples drew from his teachings.

Prodicus of Ceos and Hippias of Elis

Prodicus was a contemporary with Democritus and Gorgias, and was a disciple of Protagoras. Originally from Iulis on the island of Ceos, he was a popular public servant who eventually was sent to Athens as an ambassador. After a time, he also took up the study of philosophy and soon had opened his own school of Rhetoric. By the late fifth century B.C.E., he was giving expensive lecture-courses which seem to have emphasized linguistics. His particular specialization was the exact meaning of synonyms. His studies in religion focused on the personalization of natural objects as the creation for the need for organized religion, that man needed to understand how nature related to him personally and not how he worked in conjunction with nature. This defied many of the ideas that man was the center of the universe and that all things were created by the gods to serve man. Many of these ideas were noted in his most famous work The Choice of Heracles, a work that is no longer available but is often cited by later philosophers. Prodicus was put to death for his ideas on religion and was accused of corrupting the youth of Athens. Another contemporary Sophist was Hippias, who belonged to a school of teachers that believed that the educated man was master of everything. Once he visited the Olympic Games wearing a purple cloak, and boasted that he made everything he wore, including the ring on his finger. He dabbled in all the recognized branches of learning—grammar, rhetoric, geometry, mathematics, and music—and he also tried his hand at literature: epic poetry, tragedy, chronicles, and so on. He made profitable lecture tours, traveling from city to city; in one of the Platonic dialogues he boasts to Socrates that he had just given a very successful series of lectures in Sparta, where his subject was genealogies, which was one of the few categories of learning that were to Spartan taste. One of his works was a list of the victors at the Olympic Games, starting in 776 B.C.E. Hippias’ work is lost but it served as one source for a later list drawn up in the early third century C.E., and it is the basis for the chronology of archaic Greece.


Constructing Socrates

Often called the “father of philosophy,” Socrates (470-399 B.C.E.) is known to modern readers only through the written works of other philosophers and historians. It is unclear whether Socrates himself ever wrote down any of his philosophical views, but it is certain that any of his works that were created have since been lost. Fortunately, a good deal was written about Socrates both before and after his death. The main source of the philosophical viewpoints of Socrates comes from his disciple Plato, who first recorded the dialogues of Socrates and later used the persona of Socrates in his writing to promote his own philosophy. Three of Plato’s most famous dialogues—the Apology, the Crito and the Phaedo—recreate Socrates’ last days before he was put to death on charges of impiety and corrupting the young. All three works focus on different areas of philosophy: the Phaedo discuss death, life, and the morality of suicide; the Apology constructs a defense of philosophy in general and an attack on the Sophists’ way of thinking; and the Crito focuses on justice and issues of good versus evil even in the face of injustice. In Plato’s earlier dialogues, such as the Apology and the Euthyphro, Socrates appears as a personality in his own right, but in later works, such as the Republic—Plato’s dialogue that has had the greatest influence of anything he wrote—Socrates has become a spokesman for Plato’s own philosophy. Yet the personality of Socrates recognized by modern scholars as most authentic is Socrates as portrayed by Plato. Numerous other accounts of Socrates—such as the comical character Socrates in Aristophanes’ play Clouds and the day-to-day advisor that appears in the works of the historian Xenophon—survive, yet these accounts are considered to be minor sources in comparison to Plato.

The Identity of Socrates

Socrates was probably born in Athens in the spring of 468 B.C.E., and he lived there all his life. He was reportedly the son of a stonemason and a midwife, and he had three sons of his own—two of whom were still small children at the time of his death. His wife Xanthippe was famously ill-tempered; stories about Socrates, recorded in the works of Xenophon, include episodes of public fights between the two which often included acts of violence. (Despite the marital discord, Plato’s dialogue the Phaedo describes a tearful Xanthippe leaving Socrates’ prison cell the day before his death in 399 B.C.E., indicating the presence of genuine feelings between the two.) Socrates was a contemporary of the Sophists, and talked and argued with many of them, but the Sophists were itinerant teachers who charged tuition fees, whereas Socrates never left Athens and did not charge his disciples tuition. He originally was attracted to the doctrine of Anaxagoras, and tradition made him a pupil of Anaxagoras’ disciple, Archelaus, who kept a school in Athens; after Archelaus left Athens, Socrates probably took over as headmaster of the school. For the last twenty or 25 years of his life, he was a familiar figure on the Athenian scene, always barefoot, discussing and debating the important questions of philosophy.

Socrates’ Mission

Socrates’ mission in life was to expose the lack of wisdom in the world, a purpose that had its origins in a statement by the oracle of Apollo at Delphi that there was no one wiser than Socrates. According to Plato’s Apology Socrates did not believe the oracle, for he did not consider himself wise, so he began a quest to prove that the oracle was wrong. He encountered a man with a reputation for wisdom—Socrates did not name him—and after questioning him, he concluded that though many people, including the man himself, considered him wise, he really was not. He then examined another man who was considered wise, with the same result. He tried the politicians, then the poets and finally the skilled craftsmen, and concluded that though they might possess expertise in their own area, they were not truly wise, though they thought they were. These investigations did not make Socrates popular, as he readily admitted. Finally Socrates concluded that what the oracle meant was that he was not wise, for real wisdom belonged to God, but that he recognized his lack of wisdom and this self-recognition was what impressed the oracle. So Socrates made it his mission to seek out persons who thought they were wise and to prove to them that they were not. It was a mission that made him many enemies.

What Did Socrates Believe?

With the exception of the comic poet Aristophanes who mocked Socrates in his comedy, the Clouds, produced in 423 B.C.E., all the authors who wrote about Socrates did so after his death, and if he had any clear and coherent body of doctrine, we can discern it only dimly now. He was a traditonalist in religion insofar as he held that gods do exist and promote the welfare of mortals, and that they communicate their wishes by oracles, dreams, and other similar methods. On the other hand, he thought that all conventional beliefs needed rigorous examination, and hence he was a severe critic of Greek religion as it was practiced in the Athens that he knew. He claimed to possess a kind of inner self—adaimonion (spirit)—which guided him and warned him at times against an action he was contemplating, but nowhere do we have any explanation of what this daimonion was. He was a master of dialectic—that is, the art of investigating or debating the truth of general opinions—and his great contributions to dialectic were definition and inductive logic. He held that before any opinion can be debated, it has to be carefully defined so that there is a basis for argument. Then the argument can proceed by induction—that is, drawing general conclusions from particular facts or examples—and thus the definition can be tested and examined. Socrates was a masterful critic of irrational thought, but his philosophy is less clear since Plato used him as a mouthpiece for his own thought. It is impossible to distinguish between the philosophies of Socrates and Plato in Plato’s writings. In Plato’s Seventh Letter, so-called because it is the seventh in a collection of thirteen letters attributed him, he calls Socrates the wisest and most just man of his day, but the historical Socrates emerges from the mists of the past as a great personality and a master of rational argument rather than as the teacher of a philosophical system.

Socrates As a Rebel

Socrates was a magnet for the bright, well-to-do young men of Athens who honed their debating techniques by matching their wits with his own. Some of these pupils used the skills they learned in ways that Socrates did not intend, however, and it led to serious charges against the philosopher. It cannot be denied that Socrates taught his Athenian disciples to question the basis of the democratic constitution of Athens. The underlying assumption of democracy as it was practiced in Athens was not that all men were born equal, but that every man was capable of performing the functions that public office required, provided that he was honest. It was not necessary to have professional training to hold a government post. Hence citizens were chosen by lot to hold important public offices; the chief exceptions were the ten generals who commanded the army and navy, who were elected each year. Socrates was fond of pointing out that a person would go to a cobbler skilled at shoemaking to have his shoes made, or to a doctor trained in medicine if he was ill, but if he wanted someone to hold high office in the state, he chose a man on the street. Socrates’ logic was sound enough, but its inevitable conclusion was that cities should be governed by officials with training in government. That principle lay behind the work for which his disciple Plato is best known, the Republic, which outlines an ideal constitution for a state where those that govern are trained in the art of governing. The same theme lay behind most of the speculation about the art of government in the ancient world after Socrates. Among philosophers, democracy had, at best, lukewarm defenders. It can be argued that Socrates was the intellectual great-grandfather of the totalitarian governments of the twentieth century, but it was the unintended consequence of his teaching.

The Execution of Socrates

In 399 B.C.E., Socrates was brought to trial on a charge of heresy—not believing in the gods in which the other Greeks believed—and of corrupting the young. These charges against Socrates were less about morality and more likely the result of a political upheaval in Athens following Athens’ defeat in the Peloponnesian War five years earlier. Socrates was known to associate with men who had seized power after the war and launched a reign of terror on Athens before the democratic process could be reinstated. Socrates was also a good friend of Alcibiades, a politician who many blamed for the loss of the Peloponnesian war. Socrates was arrested and tried before 501 jurymen and, like all Athenians arraigned before the lawcourts, he was given the opportunity to speak in his own defense; no defendant could hire a lawyer to speak for him. Socrates’ defense is the basis of Plato’s Apology, which may be an accurate reconstruction of what Socrates actually did say, for Plato witnessed the trial. Though Plato portrays Socrates as speaking eloquently and convincingly to the jury, he was found guilty and sentenced to death. He was confined to the state prison until the day came for him to drink the hemlock-juice, a poison made from a weed of the carrot family that the Athenians used to execute malefactors. His last words were a reminder to his friends that he owed the sacrifice of a rooster to Asclepius, the god of healing, implying, perhaps, that death was a cure for life.

The Influence of Socrates

Many of Greece’s famous philosophers had their roots in Socrates. Antisthenes (c. 455-360 B.C.E.), considered the founder of the Cynic sect, was a devoted follower, and he in turn influenced Diogenes of Sinope, the most famous of the Cynics. Antisthenes taught that happiness was based on virtue, and virtue is based on knowledge and consequently can be taught. Aristippus of Cyrene, famous for his love of luxury, was a companion of Socrates. He was considered the forefather of the Cyrenaic school of philosophy that taught that the pleasures of the senses were the chief end of life. The Cyrenaics were to influence the Epicureans, one of the important schools of thought in the Greek world after Alexander the Great. Eucleides of Megara, another of Socrates’ pupils, established a school of philosophy in Megara on the Isthmus of Corinth, between Athens and Corinth, where he tried to combine the teaching of Socrates on ethics with the doctrine of Parmenides on the nature of the universe. Greatest of all Socrates’ pupils, however, was Plato whose works had a lasting influence on the intellectual traditions of the world.


Socrates’ Disciple

Plato (429-347 B.C.E.) was not yet thirty years old when Socrates was put to death in 399 B.C.E., and though the date of their first meeting is unknown, Socrates must already have been a middle-aged man when the two first became acquainted. The meeting of the two changed Plato’s life. He belonged to a distinguished Athenian family, and he was educated in music and gymnastics like other youths of his class. According to one tradition, he was a budding poet in his youth and had already written some tragedies, but he burned them all after he met Socrates. In the Seventh Letter, which he wrote in his old age, he reflected on the hopes of his youth. He planned to enter public life, and had an opportunity to do so in the immediate aftermath of the Peloponnesian War when a cadre of reformers overthrew the democratic constitution and took control. They were led by thirty men with absolute powers, some of them Plato’s relatives—the leader of the “Thirty,” Critias, was his mother’s cousin—and they invited him to join them. Plato was at first favorably impressed: he was young, and imagined that these reformers would establish a just state, but instead, they rapidly earned the title of the “Thirty Tyrants” by which they are known in the history books, and Plato soon realized that the democratic constitution which they had overthrown had been a very precious thing. One action in particular appalled him: the “Thirty Tyrants” tried to implicate Socrates in their crimes, but he refused and risked his life by doing so. When the “Thirty Tyrants” were overthrown, the restored democracy acted with restraint—Plato gave it credit for that—but “certain powerful persons” brought Socrates to trial on a charge of impiety. He was found guilty and put to death, and in the aftermath, many of Socrates’ acquaintances, Plato among them, feared reprisals and fled from Athens to Eucleides in neighboring Megara. Plato did not stay there long. He served in the Athenian army in 395 and 394 B.C.E. and the rest of the time he spent traveling and writing. Giving dates to Plato’s dialogues is no easy task, but it is generally agreed that his early dialogues belong to this period.

Plato’s Trip to Sicily

It was probably in 388 B.C.E. that he visited southern Italy first, and then Sicily. In southern Italy he met the Pythagorean philosopher Archytas who had been elected ruler of Tarentum, modern Taranto. Thanks to Archytas, there was a revival of Pythagoreanism in southern Italy, and he made a deep impression on Plato. The two men became friends. From southern Italy Plato went to Syracuse in Sicily where Dionysius the Elder was at the height of his power. Dionysius had enjoyed a brilliant career; at the age of 25, he had been elected general of Syracuse with full authority at a time when Carthage seemed on the verge of conquering the whole island, and he had driven back the Carthaginians and made Syracuse one of the leading cities in the Greek world. Yet by the time Plato reached Syracuse, the brilliant young savior of Greek Sicily had become a tyrant, and Plato’s portrayal of the typical tyrant found in his Republic owes a great deal to his experience with Dionysius. Dionysius had Plato removed by ship and put ashore on the island of Aegina that was at war with Athens at the time, and Plato might have been sold as a prisoner of war except that a friend from Cyrene ransomed him. During Plato’s sojourn in Syracuse, he met Dionysius’ brother-in-law, Dion, and was deeply impressed by him. In Dion, Plato recognized a man of similar ideals, and he believed he could be a potential ruler of an ideal state.

The Founding of the Academy

Upon Plato’s return to Athens, he founded his school known as the “Academy” because it occupied a park a half an hour’s walk outside the Dipylon, one of the city gates which was sacred to the guardian spirit Academus. There, under the sacred olive trees, Plato rented a gymnasium in which he started to teach, but he soon bought a parcel of land nearby which was given the name “Academy.” Little is known about the actual teaching in the Academy, but there seems to have been a regular curriculum for the students who enrolled, and mathematics was an important part of it. One anecdote held that over the Academy’s main gate was a sign that read: “No one shall enter who knows no geometry.” The Academy was a magnet for the intelligentsia of Greece, among them pioneers in mathematics, the most important of whom was Eudoxus of Cnidus who arrived in 367 B.C.E. at the age of 23 and stayed to attend Plato’s lectures. Aristotle arrived at the Academy at the age of seventeen and remained there for twenty years. It should always be remembered that the dialogues of Plato do not give us the full picture of Plato’s thought. Some aspects he transmitted orally and never committed to writing, and among these subjects were his last words on the so-called “Theory of Forms.” Thanks to the witness of Aristotle, we know that before he died, Plato lectured on one important aspect of Creation: how the ideal Forms were originally generated by the “One,” which was a divine entity, or, put simply, God. He never committed this to writing, for he did not completely trust writing as a satisfactory mode of communication.

Plato Returns to Sicily

In 367 B.C.E., the tyrant of Syracuse, Dionysius the Elder, died and was succeeded by his son, Dionysius II. His father had allowed him no experience in politics, but he was a talented young man, eager to learn, and it seemed to his uncle Dion that here was an opportunity to apply Plato’s political ideas to Syracuse. He wrote Plato, inviting him urgently to come, and in 366 B.C.E. Plato arrived to a gratifying welcome. The atmosphere soon changed, however, as court intrigues aroused Dionysius’ suspicions of Dion, and he sent him into exile. He did not allow Plato to leave until 365 B.C.E. and then only after a promise from Plato to return. Four years later, he did return, urged by Dion, who hoped that Plato could persuade Dionysius to recall him, but this time things turned out worse than before, and Plato got permission to leave Syracuse only thanks to the intervention of his friend Archytas of Tarentum. Dion now prepared for war. In 357 B.C.E., he captured Syracuse, forced Dionysius out and ruled for four years himself. Well-meaning though he was, he was tactless and authoritarian, and in 354, he was assassinated by a former supporter. Dion’s friends now appealed to Plato again, and Plato replied with two letters, the Seventh and Eighth in a collection of thirteen that are attributed to Plato. These two are thought to be genuine, though suspicion hangs over the other eleven. Plato died at the age of 81, some seven years after Dion.

Plato’s Writings

All Plato’s works (apart from the letters) are written as dialogues where he himself does not appear. The one possible exception is his last work, the Laws, where one of the interlocutors is an anonymous Athenian, who is almost certainly Plato himself. The result is that there is an elusive quality to Plato’s thought, as if he was attempting to establish a mode of thinking as much as a systematic philosophy, and that is particularly true of his early dialogues. During his time as Socrates’ disciple, he focused on issues of virtue and morality, and the importance of education and training, which interested Socrates himself in his last years. That seems clear from the dialogues that Plato produced in the aftermath of Socrates’ death, which was the catalyst that prompted him to write. Then, having recovered from the immediate shock of Socrates’ execution, Plato began to turn his attention to questions of law and government, writing his most famous text, the Republic, in response to his distaste for the sort of governments that he saw in contemporary Greece. He also wrote on metaphysics, epistemology, and ethics during his study of philosophy, but it was the nature of the just society, governed according to the principles of philosophy, that continued to occupy him. His last work, left unfinished at his death in 347 B.C.E., was the Laws in which the topic returns to that of the Republic: the constitution of a truly just state.

The Early Period

The exact order in which Plato wrote his works is not known, and assigning dates is impossible, but the dialogues can be divided into three periods: early, middle, and late. The early writings deal mainly with the teachings of Socrates in the form of dialogues. The “dialogue” seems to have been a literary form that Plato invented, borrowing it from the theater, and he used it effectively to demolish preconceived notions. One of Socrates’ main concerns is arete, the word that is always translated as “virtue,” even though there is no word in English that is an exact translation: arete means “courage” and “excellence” quite as much as “moral virtue.” The main doctrine that Socrates puts forward in almost all of the early dialogues is that this virtue is knowledge, and thus it can be taught. He does not say what knowledge is, but he does assert that no one willingly does wrong, and hence wrongdoing is a mark of ignorance. In a typical dialogue of this early period, Socrates poses a question in the form, “What is ‘X’?” For instance, what is justice? When he is offered various examples of justice, he replies that he does not want examples, he wants to know what justice is, in and of itself. Since such questions typically cannot be answered in a satisfactory way the dialogues tend to conclude on a negative note. It is not until the dialogues of Plato’s middle period—where Socrates becomes a mouthpiece for Plato’s own thought—that an attempt is made to provide positive doctrine.

The Dialogues of the Middle Period

The dialogues of the middle period include works like the Phaedo, the Symposium, and Plato’s greatest work, the Republic, which describes a utopia ruled by right principles. In these works Plato’s philosophy began to provide definite answers to the philosophical questions his master had pessimistically concluded were unanswerable. It is in these dialogues of Plato’s middle period that the “Theory of Forms” is elaborated, most explicitly in the Republic and the Phaedo. In textbooks, the “Theory of Forms” is sometimes called the “Theory of Ideas” which is misleading, for the “Ideas” are not ideas in the modern sense; rather the word simply transliterates the Greek idea which means “form.” Plato argued that these “Forms” are not mere intellectual concepts; they have an existence of their own. They are changeless and divine and among them, the form of the “Good” has a unique status. They exist separate from the things of the visible world that are imperfect copies of them, and knowledge of the “Forms” is therefore true knowledge and not mere opinion, which is fallible and changeable and easily influenced by persuasion. Thus true knowledge can exist. This is Plato’s answer to Protagoras’ dictum, “Man is the measure of all things,” which taught that all things are relative. At the same time, his logic led him to the conclusion that the “Forms” are true reality; what we see in the visible world about us is only the appearance of reality.

The Flaws in the “Theory of Forms”

There were many bright students at the Academy, and they must have made Plato aware that his “Theory of Forms” was anything but watertight. The dialogue titled the Parmenides tests the theory. We cannot assign a date to it, but it is a later work, written some years after the Republic and the Phaedo, and it is a remarkable example of self-criticism. Plato imagines his half-brother Antiphon recalling a conversation that the young Socrates had once had with Parmenides and his follower Zeno. Plato pictures Parmenides, the founder of the Eleatic school of philosophy, as an old man when this imaginary conversation took place, but his logic was as ruthless as ever. Socrates expounds the theory that there are ideal “Forms” of justice, beauty, and goodness, which belonged to the realm of true existence, though he is not prepared to assert that there are “Forms” of mud and dirt; he cannot say that absolutely everything has a “Form.” Yet he defends the core of his theory: great things are great because they partake of the Form of Greatness, and beautiful things partake of the Form of Beauty, and so on. Parmenides objects. Does the beautiful object that we see partake of all the Form of Beauty or just part of it? If it partakes of only part of it, then the “Form” must be divisible, and if all of it, then the “Form” must be in many places at once. How does the object we see partake of a Form? If a beautiful object partakes of the Form of Beauty, then the object and the Form are similar and we must posit another Form that embraces the beautiful object and the Form of Beauty. Socrates suggests that the Forms are only thoughts or concepts, but Parmenides replies that concepts must be of something. There can be no concepts of nothing. Yet we cannot know the Forms, which are absolute, for our knowledge is not absolute, and if God’s knowledge is absolute, then He cannot know us. The Parmenides concludes on an unsatisfactory note. Socrates does not abandon his “Theory of Forms” but Parmenides tells him that he needs more training in philosophy. Parmenides’ objections are not always cogent, but the dialogue bearing his name seems to show that Plato knew what the weaknesses were in his hypothesis. For Plato, the Forms were timeless entities, which—since they are timeless—cannot have been created. At the Creation, God could create the world of appearances, but he could not create the timeless Forms, for they already existed. Both Plato and Parmenides could agree that the world that we see about us is the world of appearances, not reality. Yet it is fair to ask why, if an appearance really does appear, it is not part of reality? For if appearances do not really appear, why bother about them? As Aristotle was to realize, Plato’s distinction between the Forms—which are real—and appearances—which are not—was a stumbling block.

The Republic

Plato wrote three dialogues on ideal constitutions: the Republic, the Statesman, and the Laws, his last work which he left unrevised. It is the Republic which is justly considered his greatest work, though its influence on the world of politics has not been entirely wholesome. The Republic has helped to form the intellectual background for many non-democratic governments, both communist and fascist. To understand Plato’s notions of government, it is important to consider the actual types of government that a Greek such as Plato encountered in his contemporary world. Plato lists them in the eighth book of the Republic: Timarchy, Oligarchy, Democracy, and Tyranny. Timarchy (timokrateia) was a state where the ruling principle was love of honor. Plato used the example of Sparta, which had a constitution unique on mainland Greece. Plato admired the Spartan constitution, though he recognized some of its faults. The Spartan elite—the so-called “Spartiates”—were a military aristocracy who lived off a peasant population. Known as “helots,” these serfs worked the land for their Spartiate masters, giving them half their produce. They were kept in subjection by brutal methods; Sparta had a secret police to root out any disaffection, and each year the Spartan magistrates formally declared war on the helots so that killing one of them was not murder but an act of war. The Spartiates themselves were a military caste that trained from early youth to excel in warfare. The Spartans were courageous and disciplined, and Plato admired them for it. Yet he also considered them to be slow-witted, greedy, and brutal to the underclasses. The word “oligarchy” comes from the Greeks words oligoi (few) and arche (rule), meaning to rule by a minority. In archaic Greece the minority had been aristocrats—that is, men of good family—but in Plato’s time, the minority that controlled oligarchic governments was the wealthy. Plato distrusted the profit-motive and the influence of private wealth in politics. Plato used Athens as an example of a democratic government. Athens in Plato’s day may have had as many as 300,000 residents, including men, women, slaves, and resident aliens who had little hope of acquiring citizenship, but the right to vote was restricted to male citizens. Sovereign power was vested in an assembly which was required to meet at least ten times a year, though meetings were often more frequent. At these assemblies any male citizen who attended could vote, but only a small minority did since attendance was difficult for citizens living in country villages. Plato had little respect for the system. The salient feature of democracy was liberty; individuals could do or say what they pleased, which gave society an attractive variety, but ultimately this freedom worked against social cohesion. When social cohesion failed, society disintegrated into class warfare between the rich and the poor. Finally there was tyranny, which was the personal rule of a dictator. A tyrant needed a private army for self-protection and had to eliminate all possible rivals. A tyrant, Plato argued, was essentially a criminal.

The Solution of the Republic

Having found fatal flaws in each of the existing governmental systems, Plato proposed his ideal constitution. According to Plato’s system of government, the lawgiver whose task it was to establish this utopia set up three groups or classes. The first class, composed of “Guardians,” was in charge of ruling and would have to be carefully educated and pass exacting tests before being accepted as Guardians. Once this class was selected by the lawgiver, it perpetuated itself by heredity, though occasionally an unsatisfactory son of a Guardian would have to be degraded. The next class was the “Auxiliaries” who carried out the duties of the military, police, and executive offices under orders from the Guardians. The third class was composed of the craftsmen, traders, and the like. Plato believed that men fitted to be shoemakers or carpenters should stick to their own trades and leave the ruling positions to those who had been specially trained for the task. To ensure that the Guardians carried out the lawgiver’s intentions, they had to be carefully fitted for their duties by education in cultural pursuits and physical training. Plato recommended that the poems of Homer and Hesiod be banned due to the fact that their portrayal of the gods was often not edifying. He also believed that their writings made their readers fear death, which could undermine the Guardians’ ability to die a fearless death in battle. Plato believed strongly in the power of the written word to influence behavior, and so suggested that the young should not read stories where the wicked are happy, or good men unhappy; he felt the poets to be too subversive, and recommended that they be banished. The other arts were not free of Plato’s censorship either, however, as he outlawed any music that was too sorrowful or too joyous. Other recommendations for an ideal state included a balanced economic state in which the Guardians would be neither rich nor poor. They would live in simple houses on simple food, as if in an army camp, and they would hold their property in common. Plato argued that girls and boys should have the same education, and advocated complete equality of the sexes. Plato’s advocacy of a strong state is most apparent in his structure of marriage and the family. He believed that marriages should be arranged for the good of the State by lot, although the rulers would actually manipulate the lots in such a way as to ensure that the best sires beget the most children. The State would then remove the children from their parents at birth and, if healthy, they would be reared by the State so that no one could know the identities of his or her biological parents. Plato believed that this system would foster a community in which children regarded all their elders as their fathers and mothers. To make it all work, Plato was not averse to the state propagating certain falsehoods—”Noble Lies,” as Plato called them—of which the most important was that God created three species of men: the men of gold, fitted to be Guardians; the men of silver, fit to be soldiers; and the common man of bronze and iron, fit for manual toil. Thus the bulwark of Plato’s utopia was a lethal mixture of religious propaganda and political science, but in Plato’s view, the result would be “justice,” for everyone would have his proper slot in the political structure, and be satisfied with it.

Plato’s Last Words on the Ideal State

Plato returned twice to the question of ideal government. In the Statesman, he repeated the view that government is a job for experts. He believed that the best government is rule by an expert, like the ideal lawgiver who laid out the constitution in his Republic, but if no such expert could be found, then a law-abiding monarchy was the best alternative. In his last work, the Laws, Plato once again considered the question of what sort of government would rule a city best. It is a remarkably detailed work which shows that Plato’s thought had evolved a good deal since he produced the Republic. For one thing, he placed much higher value now on the rule of law. He believed that complete obedience to the laws solves the problems of political strife. Another change is evident in that philosophy had been a vitally necessary ingredient in the Republic, but in the Laws philosophy yields pride of place to religion. Plato went so far as to suggest that atheists in the ideal state of the Laws should be converted or killed. This seems to represent a remarkable change of heart in Plato’s old age.

The Immortality of the Soul

In the Apology, which is Plato’s earliest dialogue, he muses on what happens after death. Plato determines that it will either be a dreamless sleep from which there is no awakening, or the soul will migrate to another place where one can meet with the great men of the past, such as Orpheus and Hesiod and Homer. Death is not to be feared. In the Phaedo, Plato imagines Socrates speaking to his friends on the last day of his life, and explaining what happens at death. The soul separates from the body that has prevented it from acquiring true knowledge due to the body’s constant interruptions and distractions from man’s quest for Truth. Once the soul is free of the body, it can gain direct knowledge of all that is pure and uncontaminated, that is, the Truth. Thus like a man who chooses to follow a wife or children whom he loves into the next world in the hope of seeing them there, the true philosopher will gladly make the journey into the next world to discover Truth. The final book of the Republic ends with a vision of life after death: the so-called “Myth of Er.” According to the myth, Er was apparently killed in battle, but ten days later, while he was on the funeral pyre, he revived and told an amazing tale. His soul had left his body and gone on a long journey. It had seen the righteous separated from the unrighteous who were condemned to punishment. The souls of the righteous then drew lots for the lives that they would live in their next life, and having made their choices, they traversed the desert plain of Amnesia and camped in the evening on the banks of Lethe, the stream of Forgetfulness. All were required to drink its water, and those who were imprudent drank too much and forgot everything. Er, however, was not allowed to drink, and his soul rejoined his body still remembering what it had seen. The Phaedo shows the soul anxious to leave behind the encumbering body to attain the Truth, and the “Myth of Er” tells how it must transmigrate from one life to another before it can attain the Truth. Taken together, they present a picture of the immortal soul seeking to escape from the world of appearances, represented by the body, and reach the realm of real Goodness and Truth.

Plato’s Universe

The Timaeus, one of Plato’s last dialogues, was also one of his most influential during the medieval period, partly because the first 53 chapters were available in a Latin translation during the European “Dark Ages” and partly because it presents theology rather than philosophy and thus conformed to the mindset of the medieval world. Plato’s construction of the universe rests on his basic premise that there are two orders of reality: that of true existence or “Being,” inhabited by the “Forms”; and that of apparent reality, the world of “Becoming,” the created world inhabited by the transient things perceived by our senses. The Timaeus describes how the world of “Becoming” came into existence, through the character of Timaeus, a Pythagorean philosopher from southern Italy. In the dialogue, Timaeus describes the creation of the world as being similar to the creation of a model by a craftsman. Just as the craftsman works with a model, so the Creator, who is a divine craftsman, created the world of “Becoming” using as his models the Forms that belong to the world of “Being.” His material was composed of the four elements—earth, air, fire, and water—though later in the dialogue we learn that the Creator had found his material as a confused mass in the so-called “Receptacle of Being” and reduced it to form the geometrical shapes of the four elements. The universe itself was a geometrical construction: the planets move in rings around the earth. This concept of planetary movement proved influential to men of science centuries later. In the second century C.E. Claudius Ptolemaeus of Alexandria, better known as Ptolemy, refined the system using trigonometry. Then in the sixteenth century C.E., Nicolaus Copernicus (1473-1543) showed that the earth moved around the sun, but he retained the circles of the planets that Plato described. Then Johann Kepler (1571-1630) showed that the planets moved in ellipses, and Sir Isaac Newton (1642-1727) showed that they were not regular ellipses, and Plato’s concept of a universe constructed according to the principles of geometry perished at last. The Timaeus survives as an interesting monument in the history of science but nothing more.



Aristotle (384-322 B.C.E.) was a philosopher whose achievement has been fundamental to the subsequent development of Western philosophy. No field of knowledge was beyond his purview, and for 2,000 years, his influence on European thought was supreme. It eventually became a straitjacket; from the start of the seventeenth century C.E., almost every new direction in the humanities and science had to start by overthrowing some Aristotelean doctrine, for after Aristotle, Europe never produced even his approximate equal until the Renaissance. Hence Aristotle’s philosophy ultimately became unchallenged doctrine and his writings remained “holy writ” for a thousand years. That was not Aristotle’s fault, however, but the fault of his disciples in the medieval period. In his own day, he set philosophy in a new direction. He learned from Plato, but he tempered Plato with common sense. He emphasized research and observation, and although he never developed the modern scientific experiment, he was groping in that direction. Politics was one of his interests, but he did not waste his time on utopias; rather he examined governments that actually existed in the Mediterranean world and analyzed how they functioned. His reality was not divided into “Being” and “Becoming” as Plato’s was, the first of which was real and the second only apparently real. Instead the two realities were fused and thus one could gain knowledge by observation, for what one observed was real. This was a necessary step before philosophers could develop anything similar to the modern scientific method.

Student of Plato

The acquisition of knowledge by observation may have been something that Aristotle learned from his father, who was the court physician of Amyntas II, king of Macedon, for by now, the medical fraternity had developed observation into a fine art in order to diagnose diseases. Physicians belonging to the medical fraternity of the Asclepiadae regularly taught their sons dissections, but Aristotle probably missed this training, for both his parents died while he was quite young. When he was about seventeen years old, he joined Plato’s Academy. He spent almost twenty years there, but though he never ceased to show affection and respect for Plato, he became less and less comfortable with Plato’s philosophy. Plato as he grew older placed increasing emphasis on mathematics and the trend continued at the Academy following his death. Aristotle, who must have suffered some natural disappointment at being passed over for the headship of the Academy, decided to leave it to conduct research in biology at Assos in the region of Troy. Following some time spent in Lesbos, he accepted the invitation—with a suitably generous salary attached—from King Philip II of Macedon to tutor his son, Alexander, who was fourteen years old. Alexander was under his tutelage for two years. Like Plato, Aristotle believed that there could be no good government until kings were philosophers or philosophers kings. Then in 336 B.C.E., Philip of Macedon was assassinated, and Alexander embarked on a series of military campaigns that would change the course of history in the Greek world. About a year later, Aristotle returned to Athens after an absence of about thirteen years and founded a school, the Lyceum.

Aristotle’s Writings

Approximately two-thirds of all of Aristotle’s writings are lost. During his twenty years at Plato’s Academy before Plato’s death, Aristotle wrote dialogues, borrowing the literary form from Plato, and they were much admired in the ancient world. None have survived but it is possible to ascertain the subject matter of some of them. He wrote on rhetoric, the art of public speaking, where Aristotle probably pointed out the importance of logic. Although Aristotle had written a dialogue during his Academy days accepting Plato’s views on the soul—that is, that it existed before birth and, after birth, it could recall the ideal forms from its previous life—his dialogue On Philosophy, most likely written after Aristotle left the Academy, dealt with the progress of mankind and indicated that Aristotle was already unhappy with Plato’s Theory of Forms. Aristotle also wrote collections of historical or scientific information, sometimes done in collaboration with students, or perhaps even done by students as assignments. One example from this group has survived: an essay on the Athenian constitution, a copy of which was unearthed in Egypt in 1890, copied on to the back of a tax register of the Roman period. One group of writings which did survive is composed of treatises which were never prepared for publication, possibly Aristotle’s lecture notes. They show an enormous range of subjects, indicating that nothing was too great or small to arouse his interest.

The Organization of Knowledge

Aristotle had an orderly mind and classified all knowledge into three categories: the productive, the practical, and the theoretical. Productive sciences have to do with making things, and their practitioners include engineers, farmers, artists, and the like. Practical sciences are concerned with how men act in various situations. They are the subject of Aristotle’s treatises titled Ethics and Politics. Theoretical knowledge has as its goal the discovery of truth. This category includes theology, mathematics, and natural science with their various subdivisions.

Aristotle on Cause

In modern thinking, the causes of something that comes into existence are the factors—both the components and the agents—that are responsible for the thing being what it is. Aristotle’s “cause” had a wider meaning; it can be translated as the “dimensions of reality.” Aristotle looked at an object and asked “Why? How? What for? What’s its material?”, which broadened the philosophical discussion that began with the Milesian philosophers back in the sixth century B.C.E. That group concerned themselves only with the material. The underlying substance of the universe was water, according to Thales, and air, according to Anaximenes. Later the Pythagoreans concerned themselves with “why?”—that is, what is the pattern that makes a thing what it is? Aristotle took the discussion a step further in pointing out that “how?” is also important: who made the object what it is, and what for?, i.e. what was the purpose in making the object. Thus everything has four causes. There is the material cause: the stuff from which it is made. For that Aristotle had to find a new term, and the term he used was hyle which means “wood,” but Aristotle used it for substance in general. There is the formal cause, which is the pattern. There is the efficient cause: the maker of the thing, whether it is a living thing like a dog or a person, or something inert like a table. The fourth cause is the final cause, which answers the question “what for?” What is the purpose for which a thing is made? Let us take a chest of drawers as an example. The material cause is the wood from which it is made. The efficient cause is the carpenter who made it, and the formal cause is the pattern that the carpenter followed. Then there is the question “what for?”—the teleological question. The purpose of the chest of drawers is to store clothes. Apply the same logic to Bowser, the family dog. The material cause is the flesh from which Bowser is made. The formal cause is not a blueprint; rather it is a species, the sort of thing we find in nature. Bowser is classified by biologists as a dog. Then there is the efficient cause: Bowser was not manufactured, rather he was generated by parents of the same species as himself. Finally there is the teleological question. Aristotle believed that everything, even the stars, had a goal that, in theory at least, could be discovered. Bowser has an inner nature what directs him to grow from a puppy into a mature dog that will become a family pet. That is Bowser’s goal. Aristotle applied these principles even to the universe where he asserted that the final cause is what he calls the “prime mover”—not a mechanical force, but an object of desire. It is “God,” but though Aristotle often calls his prime mover “God” it is not really a religious God. It is a divine force that exercises a continual attraction for everything in the universe, and this magnetism of the “prime mover” is the reason for the movement that we can see of the constellations in the night sky. They continually seek the final perfection of the “prime mover” that will allow them to rest, and they will never attain it. Aristotle’s “prime mover” is closer to “Mother Nature” than it is to any god of religion, whether pagan or non-pagan.

Aristotle the Logician

Aristotle was proud of his logic; in fact, he claimed to have produced a complete, perfect logic. Essentially he began with a proposition, which is a statement that is either true or false. If it is true, it refers either to a universal truth or a particular one, and similarly, if it is false, it must point either to a particular falsehood or a universal untruth. For instance, the sentence “All mammals are viviparous” is a general proposition. It means that all mammals reproduce through live births. Since Aristotle himself used letters instead of things to express propositions, we can express the sentence as “All X are Y.” There are four types of these simple propositions: the universal affirmative (“All X are Y”), the universal negative (“All X are not Y”), the particular affirmative (“Some X are Y”), and the particular negative (“Some X are not Y”). These four types of propositions can be further subdivided into three modes: that X is always Y, that X is of necessity Y, and that X is possibly Y. Once a proposition is proven true, it is possible to make a deduction using a form of argument called a “syllogism,” from the Greek sullogismos. A syllogism is an argument whereby, if certain things are assumed as true, then something different from what is assumed can be deduced. An example would be, “All humans are mortal. John Doe is a human. Therefore John Doe is a mortal.” The argument proceeds from a general proposition that is accepted as true, to a particular conclusion. Aristotle thought that he had discovered the key to deductive inference. Later philosophers developed Aristotle’s logic into a separate field of its own, which it never was for Aristotle, and for better or worse, it became one of his most important legacies to our intellectual tradition.

Aristotle’s Achievement

Before Aristotle, Greek philosophy had developed a profound distrust of the evidence of our senses. Parmenides and the Eleatic School were an extreme example. They held that the world perceived through the senses was not the real world. Heraclitus argued that constant change took place in the world. Plato held that the things seen in the visible world were only imperfect copies of ideal “Forms” in an invisible world. Aristotle’s study of biology, however, must have quickly demonstrated to him that if a person was to acquire knowledge about plants and animals, he would have to trust his senses. If he was to do research, he would have to observe, and study the observations of others. There is a certain common sense about Aristotle’s teachings. Aristotle continued to believe in the unity of knowledge, yet after him, researchers tended to specialize. Theophrastus, who succeeded him as head of the Lyceum, was a notable botanist. Aristoxenus, one of the most brilliant researchers at the Lyceum, wrote on music. Aristotle’s Lyceum was the forebear of modern institutes for research and advanced study.

The Stoics

Scant Historical Record

In the six centuries between the death of Alexander the Great in 323 B.C.E. and the emperor Constantine (312-337 C.E.) the dominant philosophy that commanded the allegiance of thinking people was Stoicism—named for the Stoa Poikile (Painted Stoa) where Zeno of Citium first taught the philosophy. The early development of this philosophy was not preserved in written texts until about 100 C.E., when a disciple of the Stoic philosopher Epictetus, Arrian, wrote a memoir of his master’s conversations with his students and published them as Discourses. Arrian was a Roman official and a soldier with literary tastes, and a man of his position may have had a slave trained in shorthand who could take notes while Epictetus and his students conversed. After Epictetus, the Meditations of the emperor Marcus Aurelius is the last expression of Stoic philosophy. The blanks in the historical record on Stoicism must be filled with second-hand reports of the earlier Stoics, the most important of these being the Lives of the Eminent Philosophers written by Diogenes Laertius. Without Diogenes’ biography of Zeno of Citium, the founder of the Stoic school, and his successors Cleanthes and Chrysippus, it would be impossible to chart the beginnings of this school.

The Cosmopolitan Nature of Stoicism

Diogenes the Cynic used to say that he was a polites (citizen) of the kosmos (world) which created the word “cosmopolitan.” Philosophy was outgrowing the intellectual world of the polis (city-state) and the checklist of the native cities of the great Stoics proves the point. The founders of the School did not come from Athens, the seat of Greek philosophy. Zeno was a Hellenized Syrian who came from Citium, a city in Cyprus. His successor as head of the school was Cleanthes who came from Assos in the Troad, the region of northwest Asia Minor in the vicinity of Troy. He had been a boxer in his earlier career and when he came to Athens, he worked as a gardener while he attended the lectures at theStoa Poikile. Chrysippus (c. 280-207 B.C.E.), the third head of the Stoic School, came either from Soli or from nearby Tarsus, both in the region of Asia Minor known as Cilicia. The next head of the school was Zeno from Tarsus; after him came Diogenes of Babylon followed by Antipater of Tarsus. After Antipater of Tarsus, Stoicism underwent a revision by the next successor, Panaetius of Rhodes, and a period of history in the philosophy known as the “Middle Stoa” began. This included a change from the rigid practices of the philosophy to a strong focus on humanism and social practice. Because of the revision, many of the prominent figures in Rome converted to Stocisim. Panaetius’s writings would influence Cato the younger, the stubborn defender of the Roman republic against Julius Caesar; Marcus Brutus, who was one of Caesar’s assassins; and Cicero, Caesar’s contemporary, who was an eclectic philosopher, picking and choosing his doctrines from several schools. Cicero favored the scepticism of the Academy, but he also ascribed to some of the teachings of Stoicism. Finally in its last phase, Stoicism became the doctrine of the Roman upper classes under the empire, and in the first century C.E. the Roman aristocrats who were martyred for their resistance to the growing autocracy of the emperors all professed Stoicism.

Stoic Physics

Zeno, the founder of Stoicism, divided knowledge into three divisions: natural philosophy, ethics, and logic. Stoic physical doctrine rejected the atomic theory of the Epicureans. “Nothing that is incorporeal exists” was the fundamental principle of Stoic physics, and hence there was no place for void. For the Stoics, matter was continuous and empty space did not exist within the finite universe, but only outside it. Everything, even the soul and God himself, was material. In determining what this material was, the Stoics looked back to Heraclitus and argued that it was Fire. Fire was the logos, the divine reason. Logos pervades the universe as honey pervades a honeycomb, and the human soul was a portion of this logos. The primal fire which is the logos is God, and hence the soul proceeds into the body from God. Periodically the whole world turns to fire and there is a great conflagration that is not so much a destruction of the world as its apotheosis (elevation to divine status), for the world that is consumed by fire has become united with God. Then the fire goes out, and history begins a new cycle, repeating itself in exactly the same way as it unfolded before. History repeats itself in endless cycles.

The Theory of Knowledge

According to Stoic doctrine, all knowledge reaches the mind through the senses. This view was in stark opposition to Plato’s doctrine, that the senses were the source of illusion and error. There was no place for Plato’s Theory of Forms in Stoic logic. For the Stoics, concepts have no reality outside the consciousness. They are merely ideas that the mind forms from the evidence with which the senses have supplied it. Virtue is based on knowledge, but to possess knowledge, the conceptions of the mind must mesh with reality, and so the wise man is one who has an accurate grasp of the real world. The Stoics believed it was possible to accurately grasp the real world, and they tried to show how the mind can acquire conceptions that are based on reality.

The Virtuous Life

“Live in harmony with nature” was the watchword of the Stoics, that is, nature in a broad sense. The guiding principle of nature is the logos—that is, reason—which the Stoics identified with God. It manifests itself in both fate or divine necessity, and divine providence. Virtue consists of living in harmony with the guiding principle of nature—that is, thelogos—and to be virtuous is the only good; the only evil is not to be virtuous. The Stoics, with some exceptions, admitted that a wise man might choose to avoid illness or death or seek self-preservation if he could do so and still act virtuously. Nonetheless, pain and discomfort should not affect his happiness, nor, for that matter, should their opposites, pleasure and good health. The wise man will be indifferent to such things. Pleasure and favor will not influence him, and so he will be completely just. Nor will he consider pain and death evils, and so he will be absolutely courageous.

Personal Conduct

Zeno defined emotion as an irrational movement of the soul, and so freedom from emotion is the mark of a wise man. A wise man is indifferent equally to fame and obscurity, and so he is devoid of conceit. Good men are not meddlesome; they decline to take any action that is outside the path of duty. Good men may drink wine, but they will refrain from drinking so much as to become intoxicated. The Stoics held that all sins were equal, for every falsehood is false, not more or less false than any other. If one man is a hundred miles from Rome and another man only five miles distant, they are both equally not in Rome. Good men are by nature sociable, and so they will not live in solitude. There should be no Stoic hermits. Finally, if a wise man has a good reason for it, he will commit suicide, or “make an exit” as the Stoics called it, either for the sake of his country or his friends, or because he is suffering great pain of incurable disease. Death as a Stoic was greatly admired in Rome where Cato the Younger became the paradigm of a Stoic martyr. Julius Caesar crossed the Rubicon River in 49 B.C.E. and drove the forces of the defenders of the republic—most of them upper-class Romans—out of Italy and defeated them at Pharsalia in northern Greece. Cato the Younger, an obstinate defender of republican ideals as he interpreted them, managed to rally the republican forces in north Africa, and in 46 B.C.E. Julius Caesar defeated them at Thapsus. Cato heard the news of the defeat at Utica near Carthage and committed suicide, refusing to survive the Roman republic. His suicide won him an acclaim which he had not enjoyed in his political career, for he was an unpleasant man and utterly uncompromising in politics. He became Cato Uticensis (Cato of Utica) who “made an exit” at Utica and thus became a martyr for republican freedom both in ancient Rome and in modern Europe. Seneca the Younger (c. 3 B.C.E.-65 C.E.), the emperor Nero’s discarded tutor, made an equally edifying exit. He was accused, justly or unjustly, of being party to a conspiracy to murder Nero and put a new emperor on the throne. Nero decided that Seneca must die, and Seneca committed suicide. He was given no time to make a will, and so he told his family that he left them something far better than earthly wealth: the example of a virtuous life, and then, opening his veins, dictated his last words to his secretary as his life ebbed away. During his lifetime, Seneca had shown a remarkable appetite for earthly wealth, but he died as a Stoic philosopher should.

Other Philosophies in the Hellenistic World

Philosophy in a Changed World

Alexander the Great died in Babylon in 323 B.C.E., having radically changed the Greek world through a series of conquests that unified Greece and brought Persia into the Hellenistic world. The word “Hellenistic” comes from the Greek hellenizein which means “to speak Greek,” and with the Greek language, to acquire a smattering of Greek culture. The Hellenistic world embraced regions that had been foreign to the Greeks of the classical period in the fifth century B.C.E. and it is significant that non-Greeks developed the dominant philosophy of the Hellenistic world and the Roman world after it: Stoicism. While the pre-Socratic philosophers had focused on abstract questions on the nature of goodness and aspects of society, the burning questions on the minds of the philosophers in this day and age focused more on how an individual should live in a world that had changed so dramatically within a generation and the achievement of personal happiness.

The Academy and the Lyceum

Plato’s Academy continued in this new era, though its reputation declined. Plato’s nephew Speusippus became head after Plato’s death, and he adhered to Plato’s doctrines although he did not emulate Plato’s temperament. He had a reputation as a man of violent passions; once, in a rage, he threw a puppy down a well. Xenocrates next took on the role of headmaster, and although he wrote an enormous number of works, none of them survived. In fact, none of the writings of Plato’s successors survived. About 265 B.C.E. Arcesilaus, a pupil of Theophrastus, Aristotle’s successor as head of the Lyceum, became head of the Academy, or scholarch, as the head was called, and began a new era: the so-called “New Academy,” which became an opponent of Stoicism. The Stoics claimed that there was a kind of sense-perception that was convincing and irresistible, and that these senses conveyed truth. Arcesilaus retorted that wrong perceptions could be as convincing as right ones—it all depended on the circumstances—and from that argument, he went on to deny the possibility of any knowledge. The Academy became somewhat less dogmatic as time went on. Yet Arcesilaus’ legacy was to make the Academy a center for logical scepticism.


Thanks to Arcesilaus, scepticism began to exercise considerable influence on Greek philosophy, but he was not the founder of the school. It was Pyrrho of Elis (c. 360-c. 270 B.C.E.) who taught that the aim of life was a serene mind, which can only be achieved if we understand our relation to the nature of things. But since we cannot know the nature of things, we should not trouble ourselves about matters we cannot understand. This doctrine is sometimes called “Pyrrhonism.” It holds that we should refrain from making positive or negative judgments, and by maintaining a balance between “yes” and “no” in our judgment we can create balance in our soul.

The Cynics

The Cynics liked to claim descent from Antisthenes, who was one of Socrates’ disciples, for that gave them a connection with the great master of classical philosophy, but the term “cynic” (doglike) was first applied to Diogenes of Sinope as a comment on the anti-social life he chose to live. He held that actions based on natural instincts and impulses could not be unnatural, and hence he refused to be bound by an social conventions. He believed a man should be free to say and do whatever he wanted—even to have sexual intercourse in public, if a natural impulse drove him in that direction. Antisthenes pointed to self-denial as the chief principle of a philosophic life, but Diogenes carried self-denial and the simple life to extremes. Legend has it that one day he saw a child drinking water by cupping it in his hands and raising them to his mouth, whereupon he threw away his own cup, saying that the child had outdone him in austerity. He was a street person—that is, he made his home on the streets, sleeping in porticoes and anywhere he could find shelter—and at one point, he made his home in a large storage jar called a pithos. Wealth and high rank did not impress him. There is a famous story, told by Plutarch in his Life of Alexander the Great, that Alexander came to visit him and found him basking in the sun. He asked if he could do anything for him. Diogenes asked him simply to stand aside, for he was blocking the sun. The story is probably apocryphal, but it does illustrate how little the Cynics were impressed by great men. One of Diogenes’ early disciples was Crates of Thebes who was once the teacher of Zeno of Citium, the founder of the Stoic school of philosophy. Crates gave up a large fortune to follow the life of a beggar and a preacher, and though he was an ugly man, he won the heart of his pupil Hipparchia; she also gave up everything to marry him. Crates glorified his beggar’s wallet, but that was precisely the weakness of the sect: they lived off others, thus saving their souls by using others who were too busy to save their own. Cynicism faded out gradually in the second and first centuries B.C.E., but in the first century C.E., it revived for reasons unknown. In the reign of the emperor Vespasian (69-79 B.C.E.) and his successors, there were swarms of Cynic philosophers in Rome and in the eastern provinces of the empire. Among the upper classes in Rome, resistance to the autocracy of the emperors was associated with Stoicism, but among the middle classes, it was voiced by the Cynics who always claimed the right to speak freely and frankly. They championed the principle that it was the duty of an ideal monarch to care for the welfare of his subjects; he should be like an idealized Hercules who used his great power for the good of his people, and they were fond of pointing out how far the actual conduct of the Roman emperors was from their ideal. The imperial government frequently lost patience with them and drove them from Rome.

The Cyrenaics

The Cyrenaics were a short-lived school that was founded in Cyrene in north Africa by Aristippus, who was once a disciple of Socrates. They taught that the chief end of life was sensual pleasure. This philosophy was built on the belief that the mind feels two emotions, pleasure and pain; while the first is the primary goal of all living things, the latter is what every creature avoids. Pleasure for the Cyrenaics, however, was not merely the absence of pain or discomfort; rather it consisted of a number of particular pleasures, past, present and future: memories of past pleasures, enjoyment of the pleasures of the present, and anticipation of pleasure in the future. Aristippus, who is supposedly the founder of the school (though some scholars have doubted it), was a teacher of rhetoric in Athens who was famous for his pursuit of luxury. He spent some time at the court of the tyrant of Syracuse in Sicily, Dionysius I, attracted there by the good food and the comfortable living. The chief importance of the Cyrenaics is that they influenced Epicureanism, which also taught that hedonism was the chief end of life, although the Epicureans were suspicious of the pleasures of the senses and sought pleasure by avoiding what might cause pain. The Cyrenaic school came to an end about 275 B.C.E.


Founder of Epicureanism

The English word “epicure,” meaning a person who loves good food and drink, is taken from Epicurus and the Epicureans. It is a singular distortion, for the Epicureans believed that man should restrict his desires to those that spring from the natural appetites—gourmet food and fine wines not being among them. Epicurus (341-270 B.C.E.) was a hedonist in that he believed that the proper goal of all activity was pleasure, but he had an austere definition of it, in that his definition of pleasure was simply the absence of discomfort or pain. The Epicurean ate to rid himself of the discomfort of hunger and no more. According to this philosophy, he should guard himself against anguish at the death of a close friend by having no close friends. Insatiable desire for wealth, power, and fame can never be satisfied, and so they should be avoided. Epicurus himself, the founder of the Epicurean School, was born in Samos, but his parents were Athenian citizens and he himself was educated in Athens. While there, he studied under the tutelage of a disciple of Democritus and learned Democritus’ atomic theory that he would later incorporate into his own philosophy. He taught philosophy at Mytilene on the island of Lesbos and in Lampsacus in northern Greece before returning to Athens, and it must have been in this period that he developed his view that pleasure was the chief end of life. It was not the avid pursuit of pleasure, but there was a fine line separating the Epicureans from the Cyrenaics, and the modern dictionary definition of “Epicurean” as a person who is fond of sensuous pleasure may be wrong but it is not entirely unjustified.

The Garden

About 306 B.C.E. Epicurus moved to Athens and there bought a house with a garden as quarters for a school which he founded. There he was joined by his disciples who formed a community of philosophers in the “Garden,” the name of his school. The disciples included women, for Epicurus was the first philosopher to admit women into an organized school. His community was known as a thiasos (company); it describes a band of persons such as worshipers of Dionysus who parade through the streets singing and dancing, but it also means a religious brotherhood. In his thiasos, Epicurus enjoyed a kind of adulation that approached worship. His birthday was celebrated as a festival. He was a voluminous writer, but all his major works are lost. Fortunately, Diogenes Laertius, writing in the early third century C.E., quotes four works by him: three of them letters to disciples and one, titled the Chief Doctrines, which is a collection of proverbs on ethical subjects, meant, evidently, to be committed to memory. Modern knowledge of Epicureanism expanded in 1888 with the discovery of another collection of proverbs in the Vatican Library.

Atoms and Void

Epicurus adapted the atomic theory of Democritus to the purposes of his philosophy. He actually cared very little about the theory itself but he needed a metaphysical background for his ethical doctrine, which taught that pleasure and avoidance of pain were the chief ends of life. He started from two simple points. First, nothing is created from nothing. That was an old principle of Greek philosophy, and it follows that the stuff from which the universe is made has always existed and will never pass away. The universe must also be infinite, for if it had a boundary, it would be possible to reach this boundary and puncture it. A dozen men thrusting their fists through the boundary of the universe could create a new boundary, and this process could be continued endlessly. Second, there are bodies in motion, as our eyes tell us that there is, for Epicurus was willing to trust the senses, and since there is motion, there must be empty space, that is, void, into which they can move. Thus the existence of atoms and void could be taken as proved, and since the universe is infinite, the number of atoms must also be infinite.


Epicurus explained the process of creation of objects as occurring when these atoms collided. He thought that the atoms had weight and were constantly falling. They could not fall at the same speed along parallel trajectories, however, or they would not naturally collide. So Epicurus taught that as the atoms fell, they would, purely at random, swerve to one side or the other. The swerve explained the collisions of atoms, which stuck together when they collided—they seem to have had velcro-like appendages—and group of atoms formed the objects that we see, both living and inert. The random nature of the swerve preserved free will in the universe, but it also left a great deal to chance. When an object passes away, the atoms disintegrate. Thus when an animal dies or a tree is cut down, the atoms that compose it will return to the infinite collection of atoms that move forever in a downward motion through the universe. Everything, including man, is atoms and void. Aristotle had claimed that everything that was created in nature had a purpose, or a “final cause.” Epicurus could not accept that. Yet he had to accept the fact that the creative process in nature seemed to follow patterns: men and women, for instance, are not put together at random; they have heads, arms, and legs positioned where they should be on their bodies. Dogs all seem to belong to one species. To explain that phenomenon, Epicurus developed a rudimentary theory of evolution: in the remote past, the atoms did form human being and animals at random, so that once upon a time the world was inhabited by some odd and curious creatures, and a dog might have the claws of a cat, and a man might have the lower body of a horse, like the mythical centaurs. But by trial and error, nature discovered the creatures most able to survive in the competition for life, and these formed patterns of creation. This was a “survival-of-the-fittest” argument, a precursor of Charles Darwin’s evolutionary theory.

The Gods

The Epicureans denied divine providence, but they did not discard the gods. To be sure, Epicurus had mechanistic explanations for natural phenomena such as thunder, rainbows, and earthquakes, and he argued against the belief that there was some caring, benevolent deity that watched over the world. The manifold suffering in the world was proof of the falsity of any such notion. But the Epicurean system did leave space for the gods. They were blessed, happy beings who lived in a never-never land, the intermundia, to use the Latin term for it, which means the “space between the worlds.” They lived happy lives in a perpetual state of ataraxia (tranquillity). They did not worry about the wretchedness of human society, which could only disturb their tranquillity. They were ethical ideals, for they had achieved theataraxia which was the aim of the Epicurean philosopher. There was no need to fear their wrath.

Gaining Knowledge

Epicurus’ atomic theory explained vision. Every object, he argued, threw off eidola (images), which were actually thin films of atoms which traveled through the air to our eyes. An image that struck the eyes affected the soul-atoms there, which transmitted the image to the mind. The whole process was to be understood in terms of the movement of atoms that are arranged and rearranged into patterns. All sensations were true, but Epicurus admitted that some images could be distorted. A favorite example was an oar partly in and partly out of the water that appears to be bent. Epicurus explained the distortion by claiming that the atoms of the eidola emitted by the oar collided with other atoms on their way to the eye, and thus transmitted a distorted image to the eye which in turn transmitted it to the mind. The mind, however, which is made up of very small atoms, can sort things out. The mind stores concepts—Epicurus refers to them as presuppositions—of what objects such as oars look like, which it has gained from experience. If a person makes the mistake of believing that the oar really is bent, it is because that person assumed too soon that the image that has reached the eyes is accurate. It follows that a person can accept the evidence received by the eyes so long as the objects that are seen are clearly visible. Senses can provide a person with accurate information.

The Fear of Death

The aim of life was pleasure—the satisfaction of desires—though Epicurus never went as far as the Cyrenaics who held that sensual pleasure was the aim of life. Fear of death was one thing that could disturb the life of ataraxia, and yet there was no reason for such fear. Death was a dissolution of the atoms. The mind, which was also made up of atoms, did not survive death. There was no need to fear tortures in the Underworld, or any of the travails that, according to myth, the souls of men suffered in the House of Hades. Epicurus and his followers assumed that it was the life after death that men feared, and by eliminating the afterlife, they removed a source of stress. They did not address the fact that what many persons fear is the act of dying itself.

Epicureanism In Rome

The philosophy that appealed to the Roman upper classes was Stoicism, not Epicureanism. Rome did produce one enthusiast for Epicurus’ philosophy, however: Titus Lucretius Carus, about who little is known. He probably lived from 94-55 B.C.E. He produced one long poem, divided into six books, the De Rerum Natura (On the Nature of Things), which is a splendid exposition of the physical theories of Epicurus. He explains the atomic theory of Epicurus, and in his third book, he applies it to the human soul, which is mortal. In fact the third book ends with a hymn to the mortality of the soul and the foolishness of humans who fear death. The poem was left unfinished. The Roman statesman, orator, and philosopher Cicero knew it, for he refers to it in a letter dated to 54 B.C.E., which he sent to his brother Quintus in terms that would lead us to believe that both his brother and himself had read it. Cicero himself leaned towards the scepticism which Arcesilaus had preached in the New Academy in Athens. It is also true that a center of Epicurean study developed in the region of Naples in the first century B.C.E.; a house excavated in the city of Herculaneum, which had been destroyed in 79 C.E. by the eruption of Mt. Vesuvius, contained charred rolls of papyrus apparently containing Epicurean works, most of them by the Epicurean philosopher Philodemus of Gadara (c. 110-c. 40 B.C.E.) who had a villa at Herculaneum. Now known as the Villa of the Papyri, the house must have been a gathering place for Epicureans in the early first century C.E. after Philodemus’ death.



Neoplatonism is the modern name for the philosophy taught by Plotinus who came to Rome shortly after 234 C.E. and opened a school there. Plotinus’ pupil, Porphyry, who published Plotinus’ works after his death, was largely responsible for publicizing his philosophy and incidentally, antagonizing Christian leaders who were both attracted to and repelled by Plotinus’ teachings. Porphyry in turn had a pupil named Iamblichus who founded a school in Syria. Iamblichus’ works are all lost, but his philosophic ideas lived on in Athens, where Plato’s old Academy was revitalized by Neoplatonism. The Neoplatonic Academy, which regarded itself as a direct descendant of the Academy that Plato founded, became a center for Neoplatonic doctrine until the emperor Justinian closed the school in 529 C.E., a move which marks the end of pagan philosophy. Thus Neoplatonism is the last product of the Greek philosophic tradition which went back to the Milesian philosophers in archaic Greece.

Remembering Plato

The philosophy of Plotinus harked back to Plato, though not to all of his writings. Plotinus paid no attention to Plato’s early dialogues, choosing to draw from the dialogues of Plato’s middle and late periods. Plato in his Republic referred to the “Being beyond Being” which is the Idea of the Good. The “Being beyond Being” re-emerges in Plotinus’ conception of the “One,” which is the principle of all being, and hence “beyond Being.” It is infinite and, as such, it has no attributes. It simply transcends any description or knowledge. But while the goal of Plato’s philosophy was the achievement of knowledge of the divine being, Plotinus went a step further and posited that the goal should be an actual union with the divine being. For Plotinus, the “One” is all things and yet none of them. It is formless, but it possesses a kind of true beauty, for it is the power that produces all that is beautiful. The “One” produces offspring, and its greatest offspring, second only to itself, is Intellect. Soul has the same relation to Intellect as Intellect has to the “One.” It is the source of all that lives and, as such, it must be immortal. Soul is the principle of motion. Capable of moving itself, it is the cause of movement in the world, and it is the source of life for all bodies that have souls within them. Soul, therefore, rules nature. So between the “One” and the material world there are three descending grades of reality: “Intelligence,” that is, the nous (world-mind); the psyche (world-soul); and physis (nature).

The Desire of the Soul

The soul’s desire is to attain union with the “One,” and to do that, it must itself become simple and formless. The soul must discard all awareness of intelligible realities. The union of the Soul with the “One” cannot be described. It is like the return of a wanderer to his native land. To attain this union, a person must free his soul from all outward things and turn completely within himself, rid his mind even of ideal forms and forget himself and thus come within sight of the “One.” The Soul loves God and wants to be one with him. This was not a philosophy for a person who took an active role in public life. Plato had founded his Academy as a school of future statesmen, but the world had changed since the fourth century B.C.E., and Plotinus’ philosophers withdrew and sought salvation in contemplation.

The Final Development

Porphyry’s pupil, Iamblichus (c. 250-c. 325 C.E.), after studies in Rome, returned home to Syria and founded his own school there. His ideas survive, though most of his writings do not, and what is remarkable about them is that he explicitly subordinated philosophy to theurgy, the art of communicating with God by oracles, mysticism and magic. Iamblichus imported a great many religious ideas from the East, particularly from Egypt, into Neoplatonism. In the fifth century C.E. the Neoplatonic Academy acquired new life under a scholarch (headmaster) named Proclus (412-484 C.E.). Proclus was born in Constantinople and came to Athens as a young man to study philosophy. He stayed to become the head of the Academy. Professors taught in their homes—the park-like setting where Plato himself had taught had long since disappeared—and the remains of Proclus’ house have been discovered. It was below the Acropolis, where Proclus had a good view of the Parthenon, the temple of Athena. When the gold-and-ivory cult statue of Athena was removed from the Parthenon, Proclus had a dream in which Athena appeared to him and told him that now she was ousted from her temple, she would have to make her home with him. Proclus enjoyed Athena’s favor, it was said. He and his disciples were also devotees of the Sun God, to whom they offered daily prayers. Life in the Neoplatonic Academy was almost that of a pagan monastery. In 529 C.E., the emperor Justinian closed it down, and the long tradition came to an end.