To the real and historical connection between the Christian Easter and the Jewish Passover, is due the explanation of a striking peculiarity in the Church’s year, viz., the movable feasts, of which Easter is the starting-point. Easter falls on no fixed date, because the Jewish 15th Nisan, unlike the dates of the Julian and Gregorian Calendars, varied year by year. The extent and nature of this discrepancy are caused by the Semitic Calendar. At the commencement of the Christian era, this Calendar was not only used by the Jews, but also extensively followed in Syria, Arabia, Mesopotamia, Babylon, Armenia, Osrhoëne, and in a great part of Asia Minor, although other nationalities in these countries kept each to its own Calendar. Thus, for example, the Greeks in Antioch followed the Syro-Macedonian Calendar, and so on. Where a mixed population existed in any place, different Calendars would be found in use. The special features of the Semitic, or Jewish Calendar, which concern us in this connection are the following:— 1. The Jewish day ended at sunset, and so the evening hours, from about six p.m. belonged to the following day. This caused difference in dates, for what happened according to Roman ideas at ten p.m. for example, was regarded by the Jews as happening on the following day. 2. The Jewish year was a variable lunar year, _i.e._ it consisted of twelve months, each of which began with the new moon, the full moon consequently falling on the 14th of each month. The moon completes her orbit round the earth in twenty-nine and a half days, or two orbits in fifty-nine days. The Jewish months, accordingly, varied from twenty-nine to thirty days alternately (Tischri and Nisan having thirty days), it being impossible to commence a month in the middle of a day. Thus the twelve months of the Jewish year make up 354 days. Eleven and a quarter days were required to make up the length of a solar year. Had this discrepancy not been rectified in some way, every Jewish month, and the new year as well, would, in the course of thirty years, have made the circle of the year. For, if in one year, the 1st Nisan coincided with the 1st March, in the next it would fall on the 12th, and so on.