The ruins of ancient Athens are still at the heart of the modern city, crowned by the Parthenon, the magnificent temple of Athena built in the mid-fifth century B.C. by Pericles. As Thucy-dides says, quoting Pericles’ paean to the greatness of Athens: “Mighty indeed are the marks and monuments of our empire which we have left. Future ages will wonder at us, as the present age wonders at us now.”
A short stretch of the ancient walls of Athens, built by Themistocles in 478 B.C., can still be seen in the Theseion quarter of the modern city. They are within the archaeological site of the ancient Kerameikos cemetery, which is just outside the two main gates in the Themistoclean walls, the Dipylon Gate and the Sacred Gate. The latter took its name from the Sacred Way, the route of the processions that led from Athens to the great shrine of Eleusis, while the Dipylon was the beginning of the road known as the Dromos.
From the sixth century B.C. onward many of the leading figures in Athenian history were buried along the sides of these two roads, which were part of the Demosion Sima, the state burial ground. This was where Pericles delivered his famous funeral oration in 431B.C., honoring the Athenians who fell in the first year of the Peloponnesian War. He reminded his fellow citizens that they were fighting to defend a free and democratic society that was “open to the world,” one whose “love of the things of the mind” had made their city “the school of Hellas.”
The course of the ancient Dromos is today the route of Odos Platonos, which leads from the Kerameikos cemetery to the quarter known as Academia, a distance of about one Attic mile (some 1,200 paces) outside the walls of ancient Athens. This quiet residential area takes its name from the famous Platonic Academy, whose site has been partially excavated, though there is very little left to see of the buildings of what for more than nine centuries was the most renowned school of Hellas.
The Academy was named for an ancient shrine of Hekademos, an earth-born hero of Attic mythology, who is supposed to have planted here twelve olive trees that were cuttings from Athena's sacred olive on the Acropolis, her gift to the people of Attica. Thetemenos, or sacred enclosure of the shrine, was vast, judging from the extent of the excavations, with a periphery of about half a mile. Plutarch says that the grounds were first enclosed and developed by Cimon, who transformed it “from a waterless and arid spot into a well-watered grove, with clear running tracks and shady groves.” There was already a gymnasium here by the time of Aristophanes, for in The Clouds, produced in 423 B.C., one of the characters describes the footraces that took place within the groves of academe:
You will spend your time, sleek and blooming, in the gymnasiums…. You will go down to the Academy and run races under the sacred olives with a virtuous comrade, crowned with white reeds and smelling of bindweed and careless ease and the white poplar that sheds its leaves, happy in the springtide when the plane-tree whispers to the elm.
Plato (427-347 B.C.) was born two years after the death of Pericles. He was profoundly influenced by Socrates, of whom he writes in many of his dialogues. In his dialogue Phaedo, or On the Soul, Plato describes the last hours of Socrates before he was forced to commit suicide in 399 B.C. in the state prison, having been convicted of corrupting the youth of Athens through his subversive ideas.
After the death of Socrates, Plato left Athens and traveled abroad, visiting Italy and Sicily. He returned to Athens in 386 B.C. and a few years later founded the Academy. Other schools and institutions functioned within and around the temenos of Hekademos, but in time the gymnasium founded by Plato became so famous that the name Academy came to be applied to it alone. Milton describes it in Paradise Regained as “the olive grove of Academe, Plato's retirement, where the Attic bird trills her thick-warbl'd notes the summer long.”
Virtually nothing is known of the school's formal organization or its curriculum. At least in its early years it may have been patterned on the educational system described by Plato in his Republic and Laws, particularly in Book I of the latter, where he writes that “what we have in mind is education from childhood in virtue, a training which produces a keen desire to become a perfect citizen who knows how to rule and be ruled as justice demands.”
The Academy probably corresponded to the colleges of the first European universities, with a community of scholars sharing a common table. Athenaeus of Naucratis (fl. ca. A.D. 200) writes that “the philosophers make it their business to join with their students in feasting according to certain set rules.” Plato, in the Laws, says that symposia were held according to the rules of a master of ceremonies, who must himself remain sober. Antigonus of Carystus (fl. 240 B.C.) writes that Plato did not hold these symposia just for the sake of carousing till dawn, “but that they might manifestly honor the gods and enjoy each other's companionship, and chiefly to refresh themselves with learned discussion.”
Plato's dialogues also mention some of the other philosophers who were in Athens in the time of Socrates (469-399 B.C.) and in his own era. The Parmenides is based on a supposed visit that Parmenides made to Athens in his old age, when he and his follower Zeno met the young Socrates. Plato writes that “Zeno and Parmenides once came to the Great Panathenaea. Parmenides was already quite venerable, very gray but of distinguished appearance, about sixty-five years. Zeno was at the time close to forty… Socrates was then quite young.”
Plato's dialogue Protagoras mentions a young man who goes to the Aegean island of Kos to study medicine under Hippocrates the Ascle-piad. The renowned physician Hippocrates (460-ca. 370 B.C.) of Kos was an older contemporary of Plato's. He was known as the Asclepiad because he belonged to one of the families that perpetuated the cult of Asclepios, the god of healing, whose first shrines were founded circa 500 B.C. The most famous of these healing shrines were the Asclepieia at Epidaurus, Athens, and Pergamum, besides which there were also renowned medical schools at Kos and Cnidus.
The writings of Hippocrates and his followers, the so-called Hippo-cratic Corpus, comprises some seventy works dating from his time to circa 300 b.c. Besides treatises on the various branches of medicine, they include clinical records and notes of lectures given to the general public on medical topics. One of the treatises, on deontology, or medical ethics, contains the famous Hippocratic oath, which is still taken by physicians today. One work in the Hippocratic Corpus is entitled The Sacred Disease, for the name given to epilepsy; those suffering from it were believed to be stricken by the gods. The author of this work, who may be Hippocrates himself, says that epilepsy, like all other diseases, has a natural cause, and that those who first called it sacred were merely trying to cover up their ignorance.
Plato's attitude toward the study of nature is evident from what he has Socrates say in the Phaedo There Socrates tells of how he had been attracted to the ideas of Anaxagoras because of his concept of Nous, or Mind. But he was ultimately disappointed, for he found that Anaxagoras did not use Mind to explain the element of design or order in nature, giving materialistic reasons instead. “This magnificent hope was dashed as I went on reading,” he says, “and saw that the man made no use of Mind, nor gave it any responsibility for the management of things, but mentioned as causes air and aether and water and many other strange things.”
Socrates was disillusioned by Anaxagoras and the other early natural philosophers because they only told him how things happened rather than why What Socrates was looking for was a teleological explanation, one involving evidences of design in nature, for he believed that everything in the cosmos was directed toward attaining the best possible end. Plato's own ideas in science are contained principally in the Timaeus, where he presents a cosmology that he says is “only along the lines of the likely stories we have been following.” Nevertheless, the Timaeus was enormously influential down to the time of the European Renaissance.
Plato's attitude toward astrology is revealed in the Timaeus, where he writes of the “everlasting and unwandering stars—divine, living things,” an expression echoed in medieval astrological writings. And in the Republic he speaks of the harmony of the heavenly spheres and of “the spindle of Necessity by means of which all the revolutions are turned,” suggesting that the human soul is subject to the motions of the celestial bodies.
Over the entrance of the Academy there was said to have been an inscription stating “Let no one ignorant of geometry enter here.” This probably derives from Plato's Republic, where Socrates says that “we must require those in our fine city not to neglect geometry in any way for even its by-products are not insignificant.”
Plato believed that mathematics was a prerequisite for the dialectical process that would give future leaders the philosophical insight necessary for governing a state. The mathematical study included arithmetic, plane and solid geometry, harmonics, and astronomy. Harmonics involved a study of the physics of sound as well as an analysis of the mathematical relations supposedly developed by the Pythagoreans in their researches on music. Astronomy was studied not only for its practical applications, but for what it revealed of the “true numbers” and “true motions” behind the apparent movements of the celestial bodies.
Plato's most enduring influence on science was his advice to approach the study of nature, particularly astronomy, as an exercise in geometry. Through this “geometrization of nature,” applicable only in those disciplines such as mathematical astronomy that could be suitably idealized, one can arrive at relations that were as “certain” as those in geometry. As Socrates remarks in the Republic: “Let's study astronomy by means of problems, as we do geometry, and leave the things in the sky alone.”
The principal problem in Greek astronomy was to explain the motion of the celestial bodies—the stars, sun, moon, and the five visible planets. As seen from the earth, the celestial bodies all seem to rotate daily about a point in the heavens called the celestial pole, actually the projection of the earth's north pole among the stars. This apparent motion is actually due to the axial rotation of the earth in the opposite sense. Although the sun rises in the east and sets in the west, each day its position among the stars as it rises appears to be about one degree back toward the west, making the transit of the twelve signs of the zodiac in one year, an apparent motion produced by the orbiting of the earth around the sun.
The apparent motion of typical stars in the northern sky over a two-hour period, where the center of rotation is the north celestial pole, the projection of the north geographic pole. (from Kuhn, 1957)
The apparent path of the sun through the zodiac, the so-called ecliptic, makes an angle of about 23.25 degrees with the celestial equator, the projection of the earth's equator among the stars. This is due to the fact that the earth's axis is tilted by 23.25 degrees with respect to the perpendicular of the ecliptic plane, an obliquity that is responsible for the recurring cycle of seasons. The obliquity of the ecliptic actually varies cyclically between 22.1 and 24.5 degrees over a period of about forty thousand years, and in the classical Greek era it was about 23.5 degrees.
The planets all follow paths that are close to the ecliptic, moving from east to west during the night along with the fixed stars, while from one night to the next they generally move slowly back from west to east around the zodiac. Each of the planets also exhibits a periodic retrograde motion, which shows as a loop when its path is plotted on the celestial sphere. This is due to the fact that the earth is moving in orbit around the sun, passing the slower outer planets and being itself passed by the swifter inner planets, the effect in both cases making it appear that the planet is moving backward for a time among the stars.
The apparent motion of the sun among the constellations; the effect is due to the fact that the observer, on the earth, is orbiting around the sun.
According to Simplicius (ca. 490-ca. 560), Plato posed a problem for those studying the heavens: to demonstrate “on what hypotheses the phenomena [i.e. the “appearances,” in this case the apparent retrograde motions] concerning the planets could be accounted for by uniform and ordered circular motions.”
The first solution to the problem was provided by Eudoxus of Cnidus (ca. 400-ca. 347 b.c.), a younger contemporary of Plato's at the Academy. Eudoxus was the greatest mathematician of the classical period, credited with some of the theorems that would later appear in the works of Euclid and Archimedes. He was also the leading astronomer of his era and had made careful observations of the celestial bodies from his observatory at Cnidus, on the southwestern coast of Asia Minor. (An observatory at that time would have comprised little more than a few simple instruments for sighting on the celestial bodies and determining their positions in the heavens.) Eudoxus suggested that the path of each of the five planets was the result of the uniform motion of four connected spheres, all of which had the earth as their center, but with their axes inclined to one another and rotating at different speeds, the planet being attached to the equator of the innermost sphere and the outermost one moving with the fixed stars. The motions of the sun and the moon were accounted for by three spheres each, while a single sphere sufficed for the daily rotation of the fixed stars, making a total of twenty-seven spheres for the cosmos. Eudoxus's model, known as the theory of homocentric spheres, was elaborated upon by Callipus of Cyzicus (fl. 370 b.c.), who added two spheres each for the sun and moon, as well as one each for Mercury, Venus, and Mars, to make a total of thirty-four. The theory of homocentric spheres was subsequently adopted by Aristotle as the physical model for his geocentric cosmos, using fifty-five planetary spheres plus another for the fixed stars.
The tilt of the earth's axis as the cause of the seasons.
Above: The apparent motion of the sun through the constellations Aries and Taurus. Below: The apparent motion of Mars through the constellations Aries and Taurus, showing its retrograde motion. (from Kuhn, 1957)
Aristotle (384-322 B.C.) was born at Stagira in Macedonia. His father, Nicomachus, served as physician to the Macedonian king Amyntas III, in whose court Aristotle received his early education. At the age of seventeen he moved to Athens, in order to enroll in Plato's Academy, where he remained for twenty years. After the death of Plato in 347 B.C. Aristotle moved to Assos, on the northwestern coast of Asia Minor, where he entered the service of the tyrant Hermeias. Hermeias had been a student of Plato's and sought to create at Assos the ideal state described in the Republic, inviting Aristotle and other scholars to teach there, including Theophrastus of Eresos in Lesbos.
Aristotle remained in Assos until 344 B.C., when Hermeias was executed by the Persians. He then moved across to the island of Lesbos, where he and Theophrastus continued the pioneering studies in botany they had begun at Assos. After a year there Aristotle left for the Macedonian capital of Pella to enter the service of Philip II, serving as tutor to the king's son and eventual successor, Alexander the Great.
Aristotle returned to Athens in 335 B.C., the year after Alexander succeeded to the Macedonian throne. That same year he founded a gymnasium called the Lyceum, which would rival the Academy in its fame. Aristotle continued to teach and do research in the Lyceum until 323 B.C., when the death of Alexander was followed by an anti-Macedonian movement that forced him to leave Athens and return to Macedonia; he died there the following year.
Aristotle's writings are encyclopedic in scope, including works on logic, metaphysics, rhetoric, theology, politics, economics, literature, ethics, psychology, physics, mechanics, astronomy, meteorology, cosmology, biology, botany, natural history, and zoology. Thus Montaigne was led to write of “Aristotle that hath an oare in every water, and medleth with all things.”
The dominant concept in Aristotle's philosophy of nature is the principle of teleology, the idea that natural processes are directed toward an end. This is stated most clearly in the second book of his Physics: “Now intelligent action is for the sake of an end; therefore the nature of things also is so: and as in nature. Thus if a house, e.g., had been a thing made by nature, it would have been made in the same way as it is now by art; and if things made by nature were made also by art, they would come to be in the same way as by nature.”
The main outlines of Aristotle's theory of matter and his cosmology derive from earlier Greek thought, which distinguished between the imperfect and transitory terrestrial world below the sphere of the moon and the perfect and eternal celestial region above. He took from the Milesian physicists the notion that there was one fundamental substance in nature, and reconciled this with Empedocles’ concept of the four terrestrial elements—earth, water, air, and fire—to which he added the aether of Anaxagoras as the basic substance of the celestial region.
According to Aristotle, the fundamental terrestrial substance, which he called prostyle, is completely undifferentiated. It has no qualities whatsoever; that is, it has no definite size, shape, place, weight, color, taste, smell, or the like, being in effect the utterly characterless raw material out of which the world is made. When this matter takes on various qualities it becomes one of the four terrestrial elements, and through further developments it takes on the form of the things seen in the world. Aristotle would describe this as matter taking on form. The matter is the raw material, the form is the collection of all the qualities that give an object its distinctive character. These two aspects of existence—matter and form—are inseparable, and can exist only in conjunction with one another.
Aristotle assigned to each of the four terrestrial elements two qualities, one from each of the two pairs of opposites: hot-cold and dry-moist. Thus earth was dry and cold, water cold and moist, air moist and hot, fire hot and dry. These elements were not immutable; any one of them could be transformed into any other one if either or both of its basic properties changed into its opposite.
Aristotle's cosmology arranged the four elements in order of density, with the immobile spherical earth at the center surrounded by concentric shells of water (the ocean), air (the atmosphere), and fire, which included not only flames but extraterrestrial phenomena such as lightning, rainbows, and comets. The natural motion of the terrestrial elements was to their natural place, so that if earth is displaced upward in air and released it will fall straight down, whereas air in water will rise, as does fire in air. This linear motion of the terrestrial elements is temporary since it ceases when they reach their natural place. Aristotle's theory of motion has heavier objects falling faster than those that are light, one of two of his erroneous ideas that dominated physics until the seventeenth century the other being the impossibility of a void.
Aristotle's cosmology.
According to Aristotle, the celestial region begins at the moon, beyond which are the sun, the five planets, and the fixed stars, all embedded in crystalline spheres rotating around the immobile earth. The celestial bodies are made of aether, the quintessential element, whose natural motion is circular at constant velocity, so that the motions of the celestial bodies, unlike those of the terrestrial region, are unchanging and eternal.
Heraclides Ponticus (ca. 390-after 322 B.C.), so called because he was a native of Heraclea on the Pontus (the Black Sea), was a contemporary of Aristotle's and had also studied at the Academy under Plato. His cosmology differed from that of Plato and Aristotle in at least two fundamental points, possibly because after leaving the Academy he may have studied with the Pythagoreans. The first point of difference concerned the extent of the cosmos, which Heraclides thought to be infinite rather than finite. A second difference concerned the apparent circling of the stars around the celestial pole, which Heraclides said was actually due to the rotation of the earth on its axis in the opposite sense. Simplicius, in his commentary on Aristotle, writes that “Heraclides supposed that earth is in the center and rotates while the heaven is at rest, and he thought by this supposition to save [i.e., account for] the phenomena.”
Aristotle was succeeded as head of the Lyceum by his associate Theophrastus (ca. 371-ca. 287 B.C.), to whom he bequeathed his enormous library, which included copies of all his works. Theophrastus is considered to be the second founder of the Lyceum, which he directed for thirty-seven years, reorganizing and enlarging the school.
Theophrastus was as prolific and encyclopedic as Aristotle, and Diogenes Laertius ascribes 227 books to him, most of which are now lost. Two of his extant works, the History of Plants and the Causes of Plants, have earned him the title “Father of Botany,” while his book On Stones represents the beginning of geology and mineralogy. His work on human behavior, entitled Characters, is a fascinating description of the types of people living in Athens during his time, all of whom still seem to be represented in the modern city.
Athens went through profound changes during the years that Theophrastus headed the Lyceum. In 322 B.C. the city came under the harsh rule of Antipater, one of the Diadochoi, or Successors, the Macedonian generals who divided up the empire of Alexander after his death. Cassander, another of the Diadochoi, took control of the city in 317 B.C., installing as his governor Dimitrios of Phaleron, who had studied in the Lyceum under Theophrastus. Ten years later Athens was captured by Dimitrios I of Macedonia, son of Antigonus I, another of the Diodochoi. This led to a series of civil wars that lasted for nearly half a century, and in that time the government of Athens changed hands seven times. During that interval Athens began to decline and was eventually surpassed by Alexandria, the new city that had been founded by Alexander in 331 B.C. on the Canopic branch of the Nile.
Theophrastus was succeeded as head of the Lyceum by Straton of Lampsacus (d. ca. 268 B.C.), who had been his student. Straton is credited with more than forty works, all of which are lost except for fragments. His most important works were considered to be those on physics, which is what led later writers to call him Straton the Physicist. Diogenes Laertius describes Straton as “a distinguished man who is generally known as ‘the physicist,’ because more than anyone else he devoted himself to the study of nature.”
One of Straton's writings on physics is a lost work entitled On Motion, which is discussed in a commentary by Simplicius. According to Sim-plicius, Straton was the first to demonstrate that falling bodies accelerate—that is, that their velocity increases over time. “For if one observes water pouring down from a roof and falling from a considerable height, the flow at the top is seen to be continuous, but the water at the bottom falls to the ground in discontinuous parts. This would never happen unless the water traversed each successive space more swiftly.”
Straton or one of his contemporaries may have written the Aristotelian work entitled Mechanics This contains the earliest extant statement of the law of the lever: if two objects are suspended from a lever, they will balance if their distances from the fulcrum are inversely proportional to their weights.
Two other schools of philosophy were founded in Athens late in the fourth century B.C. These were not formal institutions like the Academy and the Lyceum but more loosely organized groups that met to discuss philosophy. One of the schools, known as the Garden, was founded by Epicurus of Samos (341-270 B.C.) and the other, the Porch, was begun by Zeno of Citium (ca. 335-263 B.C.). The name of the first school stemmed from the fact that Epicurus lectured in the garden of his house, while the second was named for the Stoa Poikile, or Painted Porch, in the agora, the meeting place of Zeno and his disciples, who came to be known as the Stoics. Both Epicurus and Zeno created comprehensive philosophical systems that were divided into three parts—ethics, physics, and logic—in which the last two were subordinate to the first, whose goal was to secure happiness. According to Epicurus: “If we are not troubled with doubts about the heavens, and about the possible meaning of death, and by failures to understand the limits of pain and desire, then we should have no need of natural philosophy.”
The physics of Epicurus was based on the atomic theory, to which he added one new concept: that an atom moving through the void could at any instant “swerve” from its path. This eliminated the absolute determinism that had made the original atomic theory of Leucippus and Democritus unacceptable to those who, like the Epicureans, believed in free will. Zeno and his followers rejected the atom and the void, for they looked at nature as a continuum in all of its aspects—space, time, and matter—as well as in the propagation and sequence of physical phenomena. These twoopposing schools of thoughtabout the natureofthe cosmos—the Epicurean atoms in a void versus the continuum of the Stoics—have competed with each other from antiquity to the present, for they seem to represent antithetical ways of looking at physical reality.
Thus even as Athens was giving way to Alexandria as the intellectual center of the Greek world, it continued to be the School of Hellas, with the creation of two new philosophical systems that would take their place beside those of Plato and Aristotle in their influence on Western thought.