The Sanctus (and its Preface) is a prayer which is used in almost every rite of the Catholic and Orthodox liturgies. In the Orthodox churches it is called the Trisagion ("thrice holy"). The Preface, which may vary according to the liturgical season, states that it is good to praise God at all times, and goes on to describe the angels and how they praise God, leading up to the Sanctus itself which begins with the words "Holy, holy, holy Lord God of hosts".

The text is derived from Isaiah chapter VI.3 describing the winged seraphim around the throne of Yahweh, and Revelation IV.8, which is developed from the imagery in Isaiah.

In the liturgy it is followed by the Benedictus, whose text comes from Matthew XXI, 9. There are innumerable musical settings, generally as part of a complete mass setting.

The Sanctus figures also in the Requiem Mass.

External links

• Article at Catholic Encyclopedia