The feast of 15 August celebrates the end of Mary's earthly life and her being taken into heavenly glory; it is the principal Marian feast of the year in both East and West, but the two traditions describe it differently, and the difference is real. The Eastern and Eastern Catholic churches call it the Dormition, the "falling asleep", and their liturgy and iconography narrate her death, burial, and the finding of an empty tomb, with the apostles gathered. The Roman Catholic definition, promulgated by Pope Pius XII in 1950 in Munificentissimus Deus, was carefully worded to affirm that Mary was assumed "when the course of her earthly life was finished", deliberately leaving open the disputed question of whether she died.
The event is not recounted in the New Testament; the tradition rests on later texts and on the consensus of both churches. Popular observance is seasonal and local: herbs and first fruits are blessed in central Europe, the sea and fishing boats are blessed in Mediterranean towns, and in France the day carries the national vow made by Louis XIII in 1638. In much of the Catholic world it is a holy day of obligation and a public holiday.