After my death our beloved Church abroad will break three ways ... first the Greeks will leave us as they were never a part of us ... then those who live for this world and its glory will go to Moscow ... what will remain will be those souls faithful to Christ and His Church. ~St. Philaret of NY

Appreciating our Church Calendar

-taken from Understanding Our Church Calendar by Fr. Boris Molchanoff [† Aug 9 /22, 1963] and translated by GOC Holy Transfiguration Monastery in Boston

Having studied our Paschalion, we are irresistibly penetrated with awe at the ingenious work of the Alexandrian scientists who attained, in the Paschalion, an unalterable bond of the lunar with the solar Julian calendar. Alexandrian astronomers of the third century well knew the retardation of the Julian calendar from the sun. Nevertheless, they did not reject the Julian calendar, but wisely made use of its errors for a stable concordance with the lunar year, which lies at the basis of our Paschalion. The Julian calendar remains behind the true solar time, and the lunar one also remains behind together with the Julian calendar. “The lunar year is found to be eternally tied to the Julian one and a perpetual retardation of the former from the latter is not possible. The lag of the Julian year is equal to the lag of the lunar one. The equinox retards equally in both chronologies.”
The difference between the lunar and our Julian calendar does not exceed an hour and a half in the lapse of a thousand years. We can see for ourselves how all the Paschal full-moons calculated for thousands of years ahead in our Paschalion fall precisely on all the indicated dates of the Julian calendar, but do not at all coincide with the Gregorian calendar.
The unalterable tie of the lunar calendar with the Julian is made especially vivid by the following constant, periodical phenomena: we know that the lunar cycle equals 19 years while the solar cycle equals 28 years. Let us analyze these numbers by primary multipliers: 19=1x19; 28=4x7. What happens when we cross-multiply them? 19x4=76, i.e., that period of 76 years upon whose lapse the beginning of the lunar year coincides in precision with the beginning of the Julian one (as shown in chapter three).
Now, if we multiply 76 by 7, we arrive at 532, i.e., that period upon whose lapse, Pascha again occurs on the same days and months on which it was celebrated from the very beginning and during the whole length of the indiction.
In view of such a stable bond of the lunar year with the Julian, there can be no talk of any change from the Julian calendar, for otherwise there would unavoidably occur a violation of the entire well-formed and harmonious system of our Paschalion and the introduction of a great confusion in all Paschal calculations.
Sorrowfully, the light-minded experiment of changing the Julian calendar was made in Rome and now one can see its pitiful consequences. (It has made obedience to the holy canons, given to the Holy Church by the Holy Spirit, impossible for Rome which was forced, by the new calendar to abandon the canonical Paschalion).

Read more of:
(Scientific and Historical Background)
by Very Rev. Boris Molchanov