These concerned the date for the celebration of Easter* and occurred from the second to the eighth centuries. From their earliest history, the Eastern and Western Churches used a different basis for determination of the date. The Eastern Church followed the custom of observing it on the day on which the Jews celebrated the Passover, i.e., the fourteenth day of the month of Nisan. This meant that it might be observed on any day of the week. The Western Church always observed Easter on a Sunday. It was not until the time of Charlemagne,* however, that the present custom of observing it on the first Sunday after the full moon on or next-after the vernal equinox was firmly established throughout the West.
Polycarp traced the Eastern custom back to the Apostle John; Eusebius, the Western custom back to Xystus, bishop of Rome early in the second century. Victor I,* later in the same century, attempted unsuccessfully to impose the Western custom on the church at large. In 325 the* tried to stabilize the date of celebration, decreeing that it must be the first Sunday following the vernal equinox; but technical difficulties prevented a clear settlement of the issue. These difficulties stemmed from the use of different calendars.* Some churches followed the Jewish lunar calendar. Since this calendar was eleven days short, Easter could fall before the actual equinox, though 14 Nisan marked the full moon after the calendar equinox. Rome eventually fixed the equinox on 25 March; Alexandria, on 2l March, which was its correct date in the Julian calendar. But still other dates and methods of computation were used, especially in the Celtic churches. Though both Western and Eastern churches eventually resolved the technical difficulties and thus established a common practice within their respective jurisdictions, to this day a different method is followed in the East from that of the West, and the time of celebration can vary as much as five weeks.