63 This faith also gave rise to the feast of Corpus Christi, which was first celebrated in the diocese of Liege—especially through the efforts of the servant of God, Blessed Juliana of Mount Cornelius—and Our predecessor, Urban IV, established for the universal Church. It has also given rise to many forms of Eucharistic devotion that have, through the inspiration of God's grace, grown with each passing day. Through them the Catholic Church is eagerly striving to pay honor to Christ and to thank Him for such a great gift and to beg His mercy.
Source: Mysterium Fidei (Vatican.va)