bringing the courses of the sun and moon into an ordered numerical relation for the purpose of reckoning time. Taking as their point of departure the position of the sun at the vernal equinox, and following the movements of the moon until the sun returned to the same position, the Babylonians found that twelve revolutions of the moon were equivalent to one of the sun. While this observation is in reality, of course, only approximately true, to the first astronomers it might have appeared sufficiently exact to be regarded as the law of a divine world order. Thus, the year came to be divided into twelve months; and, since the moon presents four phases in each month, first quarter, full moon, last quarter, and new moon--an observation which long antedates astronomical calculation--the month was at once divided into four parts. Since the month has approximately twenty-eight days, the result was a _week_, comprising _seven days_. This number, therefore, was not, as has sometimes been erroneously assumed, derived from the seven planets. Rather is it true, conversely, that the number of the planets was, with a certain arbitrariness, first fixed at seven after this number, as well as twelve, had come to be regarded as _sacred_, because of its relation to the movements of the sun and moon. These numbers were believed to be written by the gods themselves in flaming letters on the sky. To the Babylonian, the sky furnished a revelation of the laws that should govern terrestrial life. The number twelve, especially, was adopted as the basis of the organization of human society. Of this oldest form of division, however, only meagre and occasional survivals have remained. We may refer to the legendary twelve tribes of pre-exilic Israel--later a source of much difficulty to Talmudic scholars, inasmuch as these tribes are not to be found in history--and also to the twelve gods of Greece, the twelve Apostles, etc. But the number twelve has not merely left its traces in legend; it has also inscribed itself in the records of history. Thus, the Athenian population originally comprised twelve divisions, there being four clans (_phyles_), each of which was composed of three _phratries_. Similarly, the colonial territory of the Greeks in Asia Minor is said to have included twelve Ionic cities. Moreover, even in later times, the Amphictyonic League, which undertook the protection of the Delphic oracle, consisted of twelve amphictyons, though this, it is true, was also connected with the division of time, each of the twelve tribal groups being entrusted with the guardianship of the shrine for one month in the year. With few unimportant exceptions, however, the number twelve, which was at one time probably very widely regnant, has lost its influence. Its place in the organization of society as well as in the regulation of other aspects of human life has been taken by a numerical system that still dominates our entire culture--the _decimal_ system.