"Greek philosophy began on May 28, 585 B.C. at six-thirteen in the evening."What a way to start a book! Clark says the comment is "partly serious and partly facetious." (3) Here's how he explains it.
"What was it then that existed after 585 B. C. but not before, and began at the ridiculous hour of 6:13 P.M.? It was on that day that there occurred an eclipse of the sun. Of course, solar eclipses had been occurring for some time, but the new characteristic was that this had been predicted by Thales, an astronomer of Miletus in Ionia. Records of celestial phenomena had been kept for centuries by the Eastern sages, but now for the first time Thales had discerned a regularity in these occurrences, had formulated a law, and had tested his formulation by a successful prediction. Together with Thale's other speculations this is called philosophy. It had not existed previously.
In a later age, the age of Kepler for instance, the formulation of an astronomical law would have been set down as a triumph of astronomy but would hardly have been called philosophy. One reason for this is that philosophy has given birth to the special sciences. When these grow to maturity, become specialized, and increase in detail, they leave the parental home and set up for themselves. At the time of Thales, however, there were no special sciences, and if was his fortune to initiate both science and philosophy.
The law by which solar eclipses can be predicted is itself an example of both. For while this law, directly applicable to sun, moon, and earth, was indubitably astronomy, yet more fundamentally it was a law, an instance of universalizing; and it is this characteristic which sets it apart as the great event of the age. The sages of the east had collected astronomical data in profusion, but they had never reduced these disconnected items of information to an orderly, unitary form. Philosophy begins with the reduction of multiplicity to unity." (5-6)I checked the Penguin Classic, Early Greek Philosophy, by Jonathan Barnes who wrote the following:
"According to tradition, Greek philosophy began in 585 BC (on 28 May) and ended eleven centuries later in AD 529. It began when Thales of Miletus, the first Greek philosopher, predicted an eclipse of the sun (hence the precise date). It ended when an edict of the Christian Emperor Justinian forbade the teaching of pagan philosophy. The tradition is inaccurate at both ends; for Thales observed but did not predict a solar eclipse, and Justinian may have wished to stamp out pagan philosophy but did not have his wish. Nevertheless, the traditional dates may stand as a convenient and memorable boundaries to the career of ancient philosophy." (xi)At any rate the next time you want to impress your friends try out Clark's statement and see where it leads. It could be quite interesting.