As early as the Seventh Century the preparation, by solemn fast, for keeping devoutly the great festival of the Assumption, is described as a custom of great antiquity. In many parts of the Church the strict fast enjoined lasted over several days. The Mass celebrated on this day is of Our Blessed Lady, on account of its being that of a vigil, and is said in purple vestments, and the hymn Gloria in excelsis is omitted.