In the Middle Ages, the celebration of liturgical feasts was as rich and varied as they were numerous; poetry and music, in particular, were used to impress on the congregation the significance of the events commemorated. Liturgical worship is in itself dramatic, with its stylized dialogues and the use of choirs. Often, as at Christmas, Epiphany, and Easter, the text of the Gospel called for a variety of roles. The Benedictines of St. Gallen, in Switzerland, in the 10th century wrote sequences, hymns, litanies, and tropes and set them to music. The tropes—elaborations of parts of the Liturgy, particularly the Introit—found universal acceptance and remained in use in various forms until the end of the 17th century. These tropes were dramatic in construction and, as their musical settings prove, were sung alternately by two choirs of men and boys, or by two halfchoirs. The history of the ecclesiastical drama begins with the trope sung as Introit of the Mass on Easter Sunday. It has come down to us in a St. Gallen manuscript dating from the time of the 10th century monk Tutilo.