Compline is the office that changes least, because night needs the same words every time. Its psalms are fixed or nearly so, led by Psalm 91, the great psalm of protection: you will not fear the terror of the night, he will cover you with his wings. Its hymn, Te lucis ante terminum, before the ending of the light, has been sung at this hour since the early Middle Ages. Its Gospel canticle is Simeon's, the Nunc Dimittis, now let your servant depart in peace, the prayer of a man ready to die, placed on the lips of everyone going to sleep in the tradition's frank acknowledgment that sleep rehearses death; the responsory before it, into your hands I commend my spirit, quotes the words of Christ on the cross, and the concluding prayer asks for a quiet night and a perfect end.
The office opens with an examination of conscience and a confession, so the day is reckoned with before it is surrendered, and it closes, in the Western tradition, with an anthem to the Mother of God sung by heart in the dark, the Salve Regina above all, whose valley of tears and after this our exile are among the most familiar phrases medieval piety produced. In monasteries the office ends with the abbot's blessing and the Great Silence begins, no speech until after the morning office. The whole service takes ten minutes, and contains, in miniature, a complete theology of endings.