On August 15, we celebrate the Feast of the Assumption of Mary (also known as the Dormition among Eastern Catholics and Eastern Orthodox), a Holy Day of Obligation for all Catholics. On November 1, 1950, Pope Pius XII, exercising papal infallibility, declared that it is a dogma of the Church “that the Immaculate Mother of God, the ever Virgin Mary, having completed the course of her earthly life, was assumed body and soul into heavenly glory.”
Dormition literally means “the falling asleep.” It is the original name for the Feast of the Assumption of the Blessed Virgin Mary, and Eastern Christians, both Catholic and Orthodox, continue to use it today.
Conclusion to Vespers on the eve of the Feast of the Dormition of the Holy Theotokos (Mother of God)