‘Recent studies of Babylonian sources have shown that we must revise former estimates of the extent to which the Greeks were indebted for the details of their astronomy to the Babylonians; the debt proves to have been much greater than had been imagined, and further researches may prove it to have been greater still.’ So wrote Sir Thomas Heath in 1932; in the previous year, Professor Filon had written, ‘It is gradually beginning to be realized that many of the achievements of Greek culture in the fields of astronomy and mathematics did not spring, fully armed, from the Hellenic brain, but had their more remote origins in the civilizations of the ancient East.’

There is available now sufficient evidence to show that a great deal of the astronomical knowledge which has come down to us from the Hellenistic period (c. 500 b.c. to a.d. 150) was not initially discovered during that period; and such new empiric discoveries as were made in that time were not all due to Greeks, for important contributions were still being made by Babylonians during the Seleucid Era.

To a large extent it seems that the Greeks kept very closely, even in astronomy, to the mode of research advocated by Plato, who said in The Republic, ‘Which things (i.e. “the variegated bodies in the heavens”) truly are to be comprehended by reason and intellect, but not by sight’. The Greeks founded a ‘school’ of theoretical astronomy and, with their highly developed mathematics, were able to go far with it; but their source-material was in very many cases not Greek.

The author of Epinomis states, ‘We may assume that whatever the Greeks take from the barbarians, they bring it to a finer perfection’. Adrastus (second century a.d.) wrote that the methods used by the Chaldeans and Egyptians in astronomy were imperfect because these people lacked physiologia; no doubt this was true, but it was people of these races who had done, and continued to do, most of the equivalent of modern observatory routine work.