What is "proslogion"

The Proslogion (Latin Proslogium; English translation, Discourse on the Existence of God), written in 1077–1078, was written as a prayer, or meditation, by the medieval cleric Anselm which serves to reflect on the attributes of God and endeavours to explain how God can have qualities which often seem contradictory. In the course of this meditation, the first known formulation of the ontological argument for the existence of God was set out.