Dormition of the Theotokos, 15 August

The Dormition of the Theotokos falls on the fifteenth of August, the date this rule records, commemorating the end of Mary's earthly life under the Eastern church's own theological framing, dormition meaning a falling asleep rather than a death in the ordinary sense. The observance's antiquity is well attested, with commemorations at Jerusalem traceable to at least the fifth century, and the feast was extended to the whole Byzantine Empire under the Emperor Maurice around the turn of the seventh century, making it one of the older fixed Marian dates on any Christian calendar.

Orthodox tradition holds, plainly and without the ambiguity the Western dogma leaves open, that Mary genuinely died before her body and soul were taken up into heaven, and the feast is prepared for by a two week fast beginning the first of August, a discipline with no equivalent attached to the parallel Western feast. That parallel feast is the Assumption, kept on the identical fifteenth of August in the Catholic Church, and the shared date across two churches that otherwise diverge sharply on questions of authority and doctrine is itself a mark of how old the underlying commemoration is, old enough to predate the split between East and West and to have been kept by both sides of it ever since, even as the theological framing each side gives the same date continued to diverge.