Fourthly, there was Christ's Passion itself. And so in order to represent His five wounds, in the fourth place, there is a fivefold signing of the cross at the words, "a pure Victim, a holy Victim, a spotless Victim, the holy bread of eternal life, and the cup of everlasting salvation."
Fifthly, the outstretching of Christ's body, and the shedding of the blood, and the fruits of the Passion, are signified by the triple signing of the cross at the words, "as many as shall receive the body and blood, may be filled with every blessing," etc.
Sixthly, Christ's threefold prayer upon the cross is represented; one for His persecutors when He said, "Father, forgive them"; the second for deliverance from death, when He cried, "My God, My God, why hast Thou forsaken Me?" the third referring to His entrance into glory, when He said, "Father, into Thy hands I commend My spirit"; and in order to denote these there is a triple signing with the cross made at the words, "Thou dost sanctify, quicken, bless."
Seventhly, the three hours during which He hung upon the cross, that is, from the sixth to the ninth hour, are represented; in signification of which we make once more a triple sign of the cross at the words, "Through Him, and with Him, and in Him."
Eighthly, the separation of His soul from the body is signified by the two subsequent crosses made over the chalice.
Ninthly, the resurrection on the third day is represented by the three crosses made at the words—"May the peace of the Lord be ever with you."
In short, we may say that the consecration of this sacrament, and the acceptance of this sacrifice, and its fruits, proceed from the virtue of the cross of Christ, and therefore wherever mention is made of these, the priest makes use of the sign of the cross.
Reply Obj. 4: After the consecration, the priest makes the sign of the cross, not for the purpose of blessing and consecrating, but only for calling to mind the virtue of the cross, and the manner of Christ's suffering, as is evident from what has been said (ad 3).
Reply Obj. 5: The actions performed by the priest in mass are not ridiculous gestures, since they are done so as to represent something else. The priest in extending his arms signifies the outstretching of Christ's arms upon the cross. He also lifts up his hands as he prays, to point out that his prayer is directed to God for the people, according to Lam. 3:41: "Let us lift up our hearts with our hands to the Lord in the heavens": and Ex. 17:11: "And when Moses lifted up his hands Israel overcame." That at times he joins his hands, and bows down, praying earnestly and humbly, denotes the humility and obedience of Christ, out of which He suffered. He closes his fingers, i.e. the thumb and first finger, after the consecration, because, with them, he had touched the consecrated body of Christ; so that if any particle cling to the fingers, it may not be scattered: and this belongs to the reverence for this sacrament.
Reply Obj. 6: Five times does the priest turn round towards the people, to denote that our Lord manifested Himself five times on the day of His Resurrection, as stated above in the treatise on Christ's Resurrection (Q. 55, A. 3, Obj. 3). But the priest greets the people seven times, namely, five times, by turning round to the people, and twice without turning round, namely, when he says, "The Lord be with you" before the "Preface," and again when he says, "May the peace of the Lord be ever with you": and this is to denote the sevenfold grace of the Holy Ghost. But a bishop, when he celebrates on festival days, in his first greeting says, "Peace be to you," which was our Lord's greeting after Resurrection, Whose person the bishop chiefly represents.