In one form or another, the Trisagion, “Holy, holy, holy is the Lord of hosts; the whole earth is full of his glory”, entered Jewish and Christian liturgy from Isaiah’s account in Isaiah 6. Before that happened, however, it is likely that it went through a significant change of meaning. Drawing on material that was familiar to him the prophet used the saying with a threatening rather than an encouraging tone. In the course of the following centuries, however, as the book of Isaiah grew, new reflections on the saying were added in the later chapters, with the result that when the book came to be translated into Greek the translator was justified in rendering the saying in the way that has become familiar to us.