There can be no doubt about the great antiquity of measuring time by a period of seven days. ( Genesis 8:10 ; 29:27 ) The origin of this division of time is a matter which has given birth to much speculation. Its antiquity is so great its observance so widespread, and it occupies so important a place in sacred things, that it must probably be thrown back as far as the creation of man. The week and the Sabbath are thus as old as man himself. A purely theological ground is thus established for the week. They who embrace this view support it by a reference to the six days creation and the divine rest on the seventh. 1st. That the week rests on a theological ground may be cheerfully acknowledged by both sides; but nothing is determined by such acknowledgment as to the original cause of adopting this division of time. Whether the week gave its sacredness to the number seven, or whether the ascendancy of that number helped to determine the dimensions of the week, it is impossible to say. 2d. The weekly division was adopted by all the Shemitic races, and, in the later period of their history at least, by the Egyptians. On the other hand, there is no reason for thinking the week known till a late period to either Greeks or Romans. So far from the week being a division of time without ground in nature, there was much to recommend its adoption. And further, the week is a most natural and nearly an exact quadri-partition of the month, so that the quarters of the moon may easily have suggested it. It is clear that if not in Pauls time, yet very soon after, the whole Roman world had adopted the hebdomadal division. Weeks, Feast of. [PENTECOST] [E] indicates this entry was also found in Easton's Bible Dictionary
Bibliography InformationSmith, William, Dr. "Entry for 'Week'". "Smith's Bible Dictionary".