§ It is noteworthy that the prophecy was given at Babylon, and the Babylonian year consisted of twelve months of thirty days. That the prophetic year is not the ordinary year is no new discovery. It was noticed sixteen centuries ago by Julias Africanus in his "Chronography", wherein he explains the seventy weeks to be weeks of "Jewish" (lunar) years, beginning with the twentieth of Artaxerxes, the fourth year of the 83rd Olympiad, and ending in the second year of the 202nd Olympiad; 475 Julian years being equal to 490 lunar years.