Definition. The term philosophy first approaches what modern society means by the word in the fourth-century B.C.E. writings of Plato; before that time the Sophist (itinerant professor of higher education) was not distinguished from the philosopher, and even in his lifetime the ownership of what was becoming a prestigious word was hotly disputed: Isocrates, essentially a teacher of rhetoric, called his subject "philosophy," but he lost this battle with Plato. The term refers to a way of thinking, not a way of expressing.

Presocratics. The first Presocratic philosophers are imperfectly known to us through fragments. Anaximander of Miletus published the first prose work of a philosophical treatise on the ultimate origin of the universe, which he maintained was impersonal. The profundity of the subject matter points to prose as the natural medium of the doctrine: the poetic accounts before him are naturally based...