 Around 425, Pope Celestine I contributed to the development of the Roman Rite by introducing the responsorial singing of a Gradual, and Cassian, Bishop of Brescia, contributed to the development of the monastic Office by adapting Egyptian monastic psalmody to Western usage.Later, around 530, St. Benedict would arrange the weekly order of monastic psalmody in his "Rule".Later, in the 6th century, Venantius Fortunatus created some of Christianity's most enduring hymns, including "Vexilla regis prodeunt" which would later become the most popular hymn of the Crusades.