The Book of Psalms is commonly known as the Psalms or the Psalter, and is divided into five sections, each closing with a doxology. The title is derived from the Greek translation, ψαλμοί (psalmoi) meaning "instrumental music" and, by extension, "the words accompanying the music". Most if not all are thought be composed by King David. The Psalms have always been an integral part of the prayers of the Christian church and especially among monks, who would generally chant all psalms in a week-long cycle. There have been many commentaries on the Psalms, but none perhaps more famous and widely used than St. Augustine's.