A polyphonic musical composition, probably of secular origin but based on a sacred text. It came into liturgical use in the thirteenth century. In its classical form it is based on the Gregorian tones of the Mass, to which it belongs. For some time instrumental accompaniments were used. But Pope St. Pius X in a motu proprio encouraged a return to older traditions. Allegri, Bach, Handel, and Mozart have composed some of the best specimens of the motet.