<P> Subsequent philosophic tradition was so influenced by Socrates as presented by Plato that it is conventional to refer to philosophy developed prior to Socrates as pre-Socratic philosophy . The periods following this, up to and after the wars of Alexander the Great, are those of "classical Greek" and "Hellenistic" philosophy . </P> <P> The convention of terming those philosophers who were active prior to Socrates the pre-Socratics gained currency with the 1903 publication of Hermann Diels' Fragmente der Vorsokratiker, although the term did not originate with him . The term is considered philosophically useful because what came to be known as the "Athenian school" (composed of Socrates, Plato, and Aristotle) signaled a profound shift in the subject matter and methods of philosophy; Friedrich Nietzsche's thesis that this shift began with Plato rather than with Socrates (hence his nomenclature of "pre-Platonic philosophy") has not prevented the predominance of the "pre-Socratic" distinction . </P> <P> The pre-Socratics were primarily concerned with cosmology, ontology and mathematics . They were distinguished from "non-philosophers" insofar as they rejected mythological explanations in favor of reasoned discourse . </P> <P> Thales of Miletus, regarded by Aristotle as the first philosopher, held that all things arise from a single material substance, water . It is not because he gave a cosmogony that John Burnet calls him the "first man of science," but because he gave a naturalistic explanation of the cosmos and supported it with reasons . According to tradition, Thales was able to predict an eclipse and taught the Egyptians how to measure the height of the pyramids . </P>

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