His transformation into a supreme Baal was doubtless assisted by the important place filled by the moon in early Babylonian culture. The moon was the measurer of time; the first calendar was a lunar one, and time was marked by the movements of the moon and not by those of the sun. It was on this account that the moon-god was called En-zu, “the lord of knowledge,” by the Sumerians; through him they learned how to regulate the year and the festivals of the gods. Astronomy had been cultivated in Babylonia from the beginning of its history, and for a nation of astronomers the moon was naturally an object of veneration and regard. It was the symbol of law and order as well as of the light that illuminated the darkness of the night. But we must notice that it was only at Ur and Harran that Sin or Nannar was thus elevated to the rank of a supreme Baal. The official theology refused to include him among the three chief gods of the land. He was, in fact, as Professor Hommel has shown, rather the Baal of the Semitics of Arabia and the West than of the Babylonians themselves, and the place occupied by his cult at Ur proves how completely this city lay outside the limits of the true Babylonia, and was peopled by an Arabian population. The sun-god was born of the moon. The lunar year preceded the solar, and to the primitive Babylonian the moon was a more important agent of culture even than the sun. Moreover, the sun seemed to rise from that world of night over which the moon held sway; the day was begotten by the night, and was accordingly reckoned from evening to evening. It is not until we come to the later age of Babylonian history that we find the old system making way for a new one, in which the day begins at midnight; and the 1st chapter of Genesis, with its “evening and morning,” perpetuates the ancient system of Babylonian astronomy. The sun-god was known under many names, and, like the moon-god, was worshipped in many of the Babylonian cities. But just as in historical times there were two chief seats of the worship of the moon-god,—at Ur in the south, and at Harran in the north,—so too there were two chief seats of the worship of the sun-god, one in Southern and the other in Northern Babylonia. The southern seat was Larsa, the northern Zimbir or Sippara on the borders of Mesopotamia. And as the moon-god of Ur was older than the moon-god of Harran, so there are reasons for thinking that the sun-god of Larsa was older than his rival at Sippara. Babylonian culture moved from south to north.