After Nineveh, the greatest city in the Assyrian dominion was Babylon. Even while under the dominion of the kings of Nineveh, Babylon appears to have possessed a special organization under its own chiefs, several of whose names――such as Beldesis (B. C. 888), and Nabonassar (B. C. 747)――have been preserved; and, together with the whole province of which it was the capital, to have pursued a special career. The peculiar element in the Babylonian society which distinguished it from that of Assyria proper, was its Chaldæan priesthood. ‘The Chaldæan order of priests,’ says Mr. Grote, ‘appear to have been peculiar to Babylon and other towns in its territory, especially between that city and the Persian Gulf; the vast, rich, and lofty temple of Belus in that city served them at once as a place of worship and an astronomical observatory; and it was the paramount ascendancy of this order which seems to have caused the Babylonian people generally to be spoken of as Chaldæans, though some writers have supposed, without any good proof, a conquest of Assyrian Babylon by barbarians called Chaldæans from the mountains near the Euxine. There were exaggerated statements respecting the antiquity of their astronomical observations,[2] which cannot be traced, as of definite and recorded date, higher than the era of Nabonassar (B. C. 747), as well as respecting the extent of their acquired knowledge, so largely blended with astrological fancies and occult influences of the heavenly bodies on human affairs. But however incomplete their knowledge may appear when judged by the standard of after-times, there can be no doubt that, compared with any of their cotemporaries of the sixth century B. C.――either Egyptians, Greeks, or Asiatics――they stood preëminent, and had much to teach, not only to Thales and Pythagoras, but even to later inquirers, such as Eudoxus and Aristotle. The conception of the revolving celestial sphere, the gnomon, and the division of the day into twelve parts, are affirmed by Herodotus to have been first taught to the Greeks by the Babylonians.’ This learned Chaldæan class seems to have pervaded the general mass of Babylonian society, as the corresponding priest-caste in Egypt pervaded Egyptian society, with this difference, that Babylonian society does not appear to have been parceled out like the Egyptian into a rigorous system of castes.