Most commonly and properly the words "sign of the cross" are used of the large cross traced from forehead to breast and from shoulder to shoulder, such as Catholics are taught to make upon themselves when they begin their prayers, and such also as the priest makes at the foot of the altar when he commences Mass with the words: "In nomine Patris et Filii et Spiritus Sancti". (At the beginning of Mass the celebrant makes the sign of the cross by placing his left hand extended under his breast; then raising his right to his forehead, which he touches with the extremities of his fingers, he says: In nomine Patris; then, touching his breast with the same hand, he says: et Filii; touching his left and right shoulders, he says; et Spiritus Sancti; and as he joins his hands again adds: Amen.)