In any case, the advent of Buddhism, by depreciating the religious practices and astrological speculations of the Brahmans, contributed to bringing on a decline of astronomy at the very time it was taking its most vigorous stand among the Greeks. We learn from a passage in Strabo that the Pramnai regarded the Brahmans as boasters and mad because they were interested in physiology and astronomy. Now, there really exists an ancient Buddhist treatise in which the predictions by the Brahmans of eclipses of the sun and of the conjunctions and oppositions of the planets, and their discussions of the appearance of comets and meteors, are treated as despicable arts and lies. It was just at this age that Hellenic culture was developed in northwest India. It held astronomy, and astrology too, in great esteem. The Milinda Panda mentions the royal astrologer as one of the principal functionaries of Menander. No doubt there were, among the Gavanas (Ionians) of Taxila and Euthydêmia, minds versed in the knowledge of the principal cosmological systems formulated among the Greeks from Thales to Aristotle, and also acquainted with all the progress in the physical and mathematical sciences that had been achieved by the Alexandrian astronomers in the last centuries before Christ. To comprehend the extent of the influence of Hellenic science, we have only to inquire what Hindu astronomy had become again at the time of the restoration of the Brahmans in the sixth century A. D. Aryabhatta teaches the rotation of the earth around its axis; maintains that the moon, naturally dark, owes its light to the rays of the sun; formulates the true theory of eclipses; assigns an elliptical form to the planetary epicycles; and demonstrates the displacement of the equinoctial and solstitial points. Varâha-Mihira devotes himself especially to astrological labors, but also has the merit of having condensed into a vast encyclopædia the _Pantcha Siddhântikâ_, the principal astronomical treatises that were current in India. And Brahmazoupta is especially famous for his revision of an older treatise, the _Brahma Siddhânta_.