The Holy Spirit gave the Psalter as a complete collection whose strength is collective: laments not isolated from praise, imprecations not isolated from confessions of sin, but all together. The whole gospel of the whole Christ is found in the whole Psalter.
Terry Johnson, “The History of Psalm Singing in the Christian Church” in Sing a New Song: Recovering Psalm Singing for the Twenty-First Century, Loc. 1109.