Greek settlement of the Aegean islands and coastal cities of Asia Minor was prompted initially by scarcity on the mainland and by attractive trading prospects. The first written versions of Homer’s epics would be composed in Ionia, whose Greek colonists were further inclined toward philosophy by daily contact with radically different cultures based on radically different concepts and traditions. The first to call himself a philosopher was Pythagoras, from the Ionian island of Samos, Thales, Anaximander, and Anaximenes were from Miletus; Heraclitus from Ephesus; Anaxagoras from Clazomenae; Xenophanes from Colophon. In the Italian colonies would appear Philolaus from Tarentum; Empedocles from Acragas; Zeno and Parmenides from Elea. North of the Ionian cities, in Thrace and in communities around the Black Sea, the names of Protagoras, Democritus, and Leucippus are added.
Knowledge of pre-Socratic philosophy is fragmentary. The greatest of the pre-Socratic philosophers, Pythagoras, may never have written anything and strictly forbade his disciples to publicize his teaching. The thought of other pre-Socratics often comes down by way of commentators who have agendas of their own. Nonetheless, the fragmentary record is complete enough to convey the scientific and metaphysical depth of thought prevailing in the late seventh and sixth centuries BCE. Though predominantly cosmocentric, the philosophical schools were not indifferent to social and psychological issues—to the problem of knowledge and the problem of conduct, and the question of the very essence of human life.
Pythagoras exemplifies the deepest and most original thought of the period. His studies in Egypt and other Middle Eastern cultures exposed him to the most developed mathematical and cosmological thinking of the age. But he was less interested in the practical purposes to which older cultures put these discoveries than in their deeper implications. He was intrigued and inspired by the marked relationship between mathematical abstractions and actually existent and observable events and things. The best known of these relationships is the Pythagorean Theorem, which is at once an abstract axiom of plane geometry and, at the same time, a relationship obtaining among all actual rectilinear triangles. An even more subtle form of the relationship is found in the relationship between numbers and music. Pythagoras is credited with the theory of musical harmony, but he was clearly interested less in this than in the larger implications arising from it. If, in fact, the full range of musical perceptions experienced as harmonious is generated by notes that stand in strict numerical relationships, it follows that the processes of perception must be grounded in similarly abstract and numerical relationships. Indeed, all of nature might be understood in just such relational terms. Taking the first four integers (the tetractys), 1, 2, 3, and 4, as primal, Pythagoras concluded that the first corresponded to the point, the second to the line, the third to the plane, and the fourth to the solid. These four integers are generative of a world of solid objects through a process that cannot be physical, for the physical world itself is produced by such means. Only the realm of soul could absorb the tetractys and then produce the material world.
Similarly, souls temporarily embodied in living persons possess truths beyond the reach and range of matter. The transitory physical objects of nature conceal that ultimate truth on which all reality depends. In Pythagoras, then, is found the tension between the abstract and the objective, the ideal and the “real,” the spiritual and the material, that is confronted time and again by succeeding generations of philosophical inquiry.
Of comparable influence was Parmenides of Elea (b. 515 BCE?), who presented his philosophy in a poem that may originally have been titled “On Nature.” Here he explored the various paths to truth; his critical guide is a goddess who leads him by way of a dialectical method. The most important conclusion he reaches is that real being is and must be eternal and unchanging and. as such, can never be discovered by the senses.