The Orthodox Church calendar is the timetable according to which the Church lives, services are performed, fasts begin. There are twelve major holidays in the Church, which are called the Twelfth. And the feast of the Trinity is one of them. Easter is considered the main Orthodox holiday, it is not even among the twelve. Easter is a "holiday" - an event that determines church life for a good third of the year. Moreover, the date of several twelfth holidays, including the Trinity, can be determined precisely by Easter.
Easter is a transitional holiday, that is, every year it happens at different times. The date of Easter is difficult to calculate, and the time of the onset of a number of important events depends on it.
Christians all over the world fast before Easter. For the Orthodox, this is Great Lent, which begins seven weeks before the Bright Resurrection of Christ. Before Lent, there are several special weeks for preparation: the week of Zacchaeus, the week of reading about the Publican and the Pharisee, the week dedicated to the prodigal son, the week of the Last Judgment (aka Maslenitsa).
That is, the preparation for Easter begins 13 weeks in advance. After Easter there is a series of holidays that are associated with it. This is Fomin's week, and the week of the Myrrh-bearing Women, Ascension,Trinity. What date the Trinity is in a particular year depends on what date Easter falls on.
Trinity happens on the fiftieth day after Easter, so it is also called Pentecost.
What is the number of the Trinity, it is easy to calculate, knowing the date of Easter or the beginning of Great Lent. To the date of Easter must be added 50 days, and to the day of the beginning of Great Lent - 14 weeks. Orthodox publishers often print small Easter calendars, where it is written what day Easter will be, and what date is the Trinity, for a decade ahead.
One week after the feast of Pentecost, Petrov Lent begins. It always ends on July 12, the day of the holy apostles Peter and Paul.
Easter and, consequently, the Trinity is early and late, and the beginning of Peter's fast can also be early and late. Since this fast always ends on July 12, its duration depends on the date of the Trinity holiday. Petrovka, that is, the Petrovsky post, is not strict, but its duration is different each time: from two weeks to six.
Any fast imposes significant restrictions on everyone who observes it. Great Lent involves not only the rejection of fast food, but also the restriction of entertainment, frequent attendance at worship. Some do not watch TV in Lent, do not go to the theater and visit. Life in fasting is changing dramatically, so the Orthodox will find out with great interest the date of Easter for next year or what date is the Trinity. For example, Trinity 2013what date? It is necessary to open Easter and find out that Easter in 2013 is very late, and the Trinity falls on June 23. This means that Great Lent will start late this year, and indeed, the beginning of Lent fell on March 15th. Everyone calmly and without worries celebrated March 8, and Easter fell on the May holidays, which is also very convenient. Petrov's post was short, only two weeks.
Some are surprised that the Orthodox use such an indefinite, different calendar each time. But besides the theological justifications, there are other positive aspects of such “instability”. Every year is different, one is not like the other, and that's not bad.
