Page:Early Greek philosophy by John Burnet, 3rd edition, 1920.djvu/36

22 They had also noted the occurrence of eclipses with a view to predicting their return for purposes of divination. But we must not exaggerate the antiquity or accuracy of these observations. It was long before the Babylonians had a satisfactory calendar, and they kept the year right only by intercalating a thirteenth month when it seemed desirable. That made a trustworthy chronology impossible, and therefore there were not and could not be any data available for astronomical purposes before the so-called era of Nabonassar (747 B.C.). The oldest astronomical document of a really scientific character which had come to light up to 1907 is dated 523 B.C., in the reign of Kambyses, when Pythagoras had already founded his school at Kroton. Moreover, the golden age of Babylonian observational astronomy is now assigned to the period after Alexander the Great, when Babylon was a Hellenistic city. Even then, though great accuracy of observation was attained, and data were accumulated which were of service to the Alexandrian astronomers, there is no evidence that Babylonian astronomy had passed beyond the empirical stage.

We shall see that Thales probably knew the cycle by means of which the Babylonians tried to predict eclipses (§ 3); but it would be a mistake to suppose that the pioneers of Greek science had any detailed knowledge of Babylonian