Sanctus - Definition and Overview

The Sanctus and its Preface, is a prayer which is used in almost every single rite of the Catholic and Orthodox liturgies. The Preface in general describes that it is good to praise God at all times, and goes on to describe in some way the angels and how they praise God, leading up to the core of the sanctus which is the words "holy, holy, holy lord god of hosts". The text is derived from Isaiah chapter VI, verse 3 and Revelation IV, 8. It is followed by the Benedictus, whose text comes from Matthew XXI, 9. There are innumberable musical settings, generally as part of a complete mass setting.

Sanctus is also a Roman cognomen derived from the Latin word for "holy".