GREEK PHILOSOPHY. The philosophy of the Greeks, which is the source of the Western philosophy of modern times, as Homer is the source of Western poetry, had its origin, not in Greece itself, but in the colonies of Asia Minor and Magna Grtecia. The earliest or pre-Socratic period may be broadly divided into the Ionic and Italic schools. Both attempted to determine the nature, origin, laws, and destiny of the visible world. The earliest definite name is the founder of the Ionic school, Thales of Miletus, who began the transition from the mythological to the scien tific interpretation of nature, and the search for an original substance or subject of reality. He was followed by Anaximander, who found this substance not in water but in indeterminate mat ter, while a third teacher of Miletus, Anaximenes, Preferred 'the definite substance of air. A little younger was the greatest of the pre-Socratic philosophers, Heraclitus. He held one substance, changing itself into all the elements known to us, but chose to name it rather from its highest po tency, fire, which exhibits most clearly the con stant movement and activity of the world.
Next comes Pythagoras of Samos, who settled at Crotona in Italy, about 529 n.c., and there founded what is known as the Italic school. In contrast to the Ionic school, which believed in one ever-changing, self-developed universe—what Ritter has called dynamical physicism—the Italic transcendental physicists found their key to the universe not in any known substance, but in num ber and proportion. After the school of Pytha goras came a second Italian school, the Eleatic, founded by Xenophanes of Colophon, who mi grated to Elea in B.O. 540. Its chief representa tive is Parmenides; his philosophy is the direct antithesis to that of Heraclitus in assuming that all that exists has existed and will exist the same forever, and that it is change and multiplicity alone which are illusory—an early idea of the in destructibility of matter.
The Ionico-Italic school represented mechanical physicism. Empedocles of Agrigentum and An axagoras, the teacher of Pericles and Euripides, agreed in accepting the Eleatic principle of the immutability of substance, while denying its ab solute oneness. Democritus of Abdera was the chief exponent of the atomic theory, which based the universe on combinations of indivisible, un changeable atoms. He closes the series of the pre-Socratic dogmatists, who devoted themselves to the investigation of nature as a whole. Be tween them and Socrates, the great regenerator of philosophy, comes the sceptical and sophistic era. The earliest of the Sophists are Protagoras of Abdera and Gorgias of Leontini; Hippias of Eleas and Prodicus of Ceos were somewhat younger. The effect of their teaching was the disintegration of established beliefs.
Socrates, while sharing the general scepticism as to natural philosophy, maintained the cer tainty of moral distinctions and laid down a method for the discovery of error and the estab lishment of truth. Among those influenced by him were certain imperfect or one-sided Socrati cists. Antisthenes, founder of the Cynic and in directly of the Stoic schools, was the caricature of the ascetic and unconventional side of Socrates. Aristippus of Cyrene, founder of the Cyrenaic school, also dwelt exclusively on the practical side of his master's teaching, holding that it was impossible to attain objective knowledge. In Hegesias the Cyrenaic doctrine finally blends with the Cynic.
The two most famous disciples of Socrates were Plato and Aristotle. While in some ways they looked at life and being from distinct points of view, giving the foundation for the famous saying that "every man is born either a Platonist or an Aristotelian," they have manifold relations. Plato's rich contributions to logic, psychology, metaphysics, ethics, and natural religion required codification. Aristotle, with perhaps the great est gifts for analytic systematization of philos ophy that have ever been seen, unconsciously ap plied himself to the task. Thus he developed Plato's dialectic method into the strict science of logic; Plato's 'ideas,' though shorn of their sep arate supra-mundane existence, survived in the Aristotelian `form' as opposed to 'matter.' With the death of Aristotle a new age begins. The fearless genius which had soared to the contemplation of supreme ideas of good, of the form and end and cause of all existence, sank back to earth. As the great pre-Socratic move ment terminated in the scepticism of the Soph ists, so this greater movement found its nat ural reaction in the scepticism of Pyrrho and the later Academy. The post-Aristotelian school were predominantly ethical, sensationalist, and materialist, as contrasted with the idealistic metaphysics of the preceding age. Of these schools the least original and the least important in the Peripatetic. The first name among the Sceptics is Pyrrho of Elis. (See KNOWLEDGE, THEORY or.) The later development of the Academy may be divided into three schools—the old, the middle or Sceptic, and the reformed or Eclectic Academy. To the first belong the names of Speusippus, Xenocrates, and Polemo, who mod ified the Platonic doctrine mainly by the admix ture of Pythagorean elements. The chief ex ponents of the middle Academy were Arcesilaus, Carneades of Cyrene, and his disciple, Clitoma chus of Carthage, who neglected the positive doc trine of Plato and employedd, themselves mainly in a negative polemic against the dogmatism of the Stoics. The reformed Academy began with Philo of Larissa, the pupil of Clitomachus and teacher of Cicero.