Cutting from an Antiphonary: Initial G[loria tibi Trinitas]: The Trinity, c. 1410. This beautiful initial comes from a choral book called an antiphonary. The text introduced by this initial is the antiphon that follows the reading of the nine psalms in the office of prime: Gloria tibi Trinitas... (Glory be to the Trinity). By the later Middle Ages, artists were representing the Trinity (Father, Son, and Holy Ghost) in the form shown here.