For the Jews, this was easy; it was the 15th Nisan in their Calendar, but for Christians of other countries, it was very difficult. In the Roman Empire, to which they all belonged, different methods of reckoning time and different calendars were in use. Since 45 B.C., the Romans themselves used the revised Julian Calendar, leaving at the same time perfect freedom to subject nations either to adopt it, or continue their own methods.[102] Chief among the existing systems were the Egyptian, the Syro-Macedonian, and the Semitic, each with its own way of dating the year. The two first systems admitted of being brought into agreement with the Roman Calendar, with more or less difficulty, since, according to them, the year began on a fixed date, but with the Jewish Calendar it was not so, for its was based on the lunar year, and never synchronised with the solar year as to the beginning of months and years. The Egyptian year, at the commencement of the Christian era, began on the 29th August, and consisted of twelve months of thirty days each, and five additional days (ἐπαγόμεναι) belonging to no month. Every fourth year was a leap-year, namely the third, seventh, eleventh, fifteenth year, according to the Julian reckoning. The Syro-Macedonian Calendar commenced with the autumnal equinox. The Syrians, however, later on, partially adopted the Julian Calendar in a somewhat modified form.[103] The Egyptian system of introducing additional days was essentially the same as the Roman, except that their leap-year was always one year in advance of the Roman leap-year. To their usual five additional days, they added yet one more, making a total of six. Consequently the next year, _i.e._ the fourth, eighth, twelfth, sixteenth, etc., began on the 30th instead of the 29th August.[104] For reckoning years, the Egyptians made use of the years of the sovereign’s reign, but as they began the year with the 1st Thoth, preceding the proclamation of the sovereign’s accession, it often happened that more years than he was entitled to were set down to one sovereign, while another who had reigned for less than a year was simply passed over.[105] It was extremely difficult for those nations, whose Calendars were arranged on a different system, to fix the day of Christ’s death by their own chronology, for the Jewish 15th Nisan might fall on widely different days, sometimes in March, sometimes in April. How difficult it was to discover, the days on which the death and resurrection of Christ ought to be commemorated, will become more obvious from what follows. 3. _The circumstances which led to Easter being a movable Feast_