A Vespers Liturgy for Christmas ‘Ad vesperas’ – literally ‘at dusk’ – indicates the hour at which monks and other clerics of the Western church joined together (and indeed continue to do so) for the evening service, one of the eight daily hours of prayer, known as the ‘offices’. The offices were generally less solemn and ornate than mass celebrations, except for Vespers, which especially in Italy reached a liturgical and musical highpoint, particularly on important feast-days in the church calendar. Like the other offices and the mass, Vespers follows a fixed pattern, whereby daily recurring texts and chants alternate with elements specifically associated with a particular feast. Among the fixed ingredients are the five psalms with their antiphons and then a hymn, all of which is crowned by the Magnificat, Mary’s song of praise upon visiting her cousin Elizabeth (Luke 1: 46-55). These texts were originally sung in monody, but later, especially starting in the 16th century, they were performed polyphonically (at least in part). In 1550 a collection of polyphonic settings of the psalms was published in Venice. The composers were Adriaan Willaert, the Flemish-born Kapell­meister of the San Marco basilica, and his French colleague Jacques Colebault, better known as Jacquet of Mantua. Choirmasters now had at their disposal a broad choice of polyphonic works with which to adorn their Vesper services.