The Psalter is the most well-known book in the religious life of our Church. It is used daily in every Service (Vespers, Orthros, Hours, etc.), and in the form of individual Psalms or verses, in the Divine Liturgy and the other Mysteries. The entire hymnology of our Church is based on it. The prophet David composed it by the divine Spirit, and for this reason its verses contain deep meanings. The Psalter is a "public treasury of teaching", a "common hospital, which contains the medicine for every passion", according to St. Basil the Great.