Catholics are taught to make the Sign of the Cross upon themselves when they begin their prayers. Since we make the Sign of the Cross before and after our prayers, many Catholics don't realize that the Sign of the Cross is a prayer itself. It should be said with reverence; we shouldn't rush through it on the way to the next prayer.

Making the Sign of the Cross Using your right hand, you should touch your forehead at the mention of the "Father"; the lower middle of your chest at the mention of the "Son"; the left shoulder on the word "Holy" and the right shoulder on the word "Spirit"; joining the hands on the word "Amen".

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 Latin): 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 he says: Amen.

Second variety of the Sign of the Cross A second variety is a of sign of the cross made in the air by bishops and priests in the blessing of persons or material objects. It is made many times in the liturgy of the Mass and in usually all the ritual offices connected with the sacraments and sacramentals.

Third variety of the Sign of the Cross A third variety is represented by the little cross, generally made with the thumb, which the priest or deacon traces upon the book of the Gospels and then upon his own forehead, lips, and breast at Mass.

History - The course of development The cross was originally traced by Christians with the thumb or finger on their own foreheads. This practice is associated in with certain references in Scripture, Ezekiel 9:4 (of the mark of the letter Tau); Exodus 17:9-14; and Apocalypse 7:3, 9:4 and 14:1. Tertullian speaks of the Christian woman "signing" her bed (cum lectulum tuum signas, "Ad uxor.", ii, 5) before retiring. The sign of the cross was traced on the lips (Jerome, "Epitaph. Paulæ") and on the heart (Prudentius, "Cathem.", vi, 129). The earliest example of a larger cross made over the whole body is possibly of the fourth or fifth century: "St. Nino began to pray and entreat God for a long time. Then she took her wooden cross and with it touched the Queen's head, her feet and her shoulders, making the sign of the cross and straightway she was cured" (Studia Biblica, V, 32).

The larger cross is likely due to Leo IV in the middle of the ninth century with his instructions to: Sign the chalice and the host with a right cross and not with circles or with a varying of the fingers, but with two fingers stretched out and the thumb hidden within them, by which the Trinity is symbolized (Georgi, "Liturg. Rom. Pont.", III, 37). During the Middle Ages the large sign of the cross was more commonly made in the West with the open hand and that the bar of the cross was traced from left to right. From the earliest period the sign of the cross has been used in exorcisms, ritual of the sacraments, blessing and consecration.