The custom of bowing the head at the mention of His Name was formally written into law at the Second Council of Lyons, A.D. 1274, convened by Pope Gregory X:
"Those who assemble in church should extol with an act of special reverence that Name which is above every Name, than which no other under Heaven has been given to people, in which believers must be saved, the Name, that is, of Jesus Christ, Who will save His people from their sins. Each should fulfill in himself that which is written for all, that at the Name of Jesus every knee should bow; whenever that glorious Name is recalled, especially during the sacred Mysteries of the Mass, everyone should bow the knees of his heart, which he can do even by a bow of his head."
From Apostolic times, the Church has professed that "at the name of Jesus every knee should bend, of those in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father" (Phil. 2:10). Through the particular efforts of St. Bernardine of Siena, devotion to the Holy Name of Jesus was promoted through the inscription of the monogram of the Holy Name (IHS) and the addition of the name Jesus to the Hail Mary. In 1597, Pope Sixtus V first granted an indulgence for the uttering of the phrase used so often by the present Holy Father and included among the pious invocations of the current Enchiridion Indulgentiarum. "Praised be Jesus Christ!"