Objection 1: It seems that this is not a suitable form of Baptism: "I baptize thee in the name of the Father, and of the Son, and of the Holy Ghost." For action should be ascribed to the principal agent rather than to the minister. Now the minister of a sacrament acts as an instrument, as stated above (Q. 64, A. 1); while the principal agent in Baptism is Christ, according to John 1:33, "He upon Whom thou shalt see the Spirit descending and remaining upon Him, He it is that baptizeth." It is therefore unbecoming for the minister to say, "I baptize thee": the more so that Ego (I) is understood in the word baptizo (I baptize), so that it seems redundant.
Obj. 2: Further, there is no need for a man who does an action, to make mention of the action done; thus he who teaches, need not say, "I teach you." Now our Lord gave at the same time the precepts both of baptizing and of teaching, when He said (Matt. 28:19): "Going, teach ye all nations," etc. Therefore there is no need in the form of Baptism to mention the action of baptizing.
Obj. 3: Further, the person baptized sometimes does not understand the words; for instance, if he be deaf, or a child. But it is useless to address such a one; according to Ecclus. 32:6: "Where there is no hearing, pour not out words." Therefore it is unfitting to address the person baptized with these words: "I baptize thee."
Obj. 4: Further, it may happen that several are baptized by several at the same time; thus the apostles on one day baptized three thousand, and on another, five thousand (Acts 2, 4). Therefore the form of Baptism should not be limited to the singular number in the words, "I baptize thee": but one should be able to say, "We baptize you."
Obj. 5: Further, Baptism derives its power from Christ's Passion. But
Baptism is sanctified by the form. Therefore it seems that Christ's
Passion should be mentioned in the form of Baptism.
Obj. 6: Further, a name signifies a thing's property. But there are three Personal Properties of the Divine Persons, as stated in the First Part (Q. 32, A. 3). Therefore we should not say, "in the name," but "in the names of the Father, and of the Son, and of the Holy Ghost."
Obj. 7: Further, the Person of the Father is designated not only by the name Father, but also by that of "Unbegotten and Begetter"; and the Son by those of "Word," "Image," and "Begotten"; and the Holy Ghost by those of "Gift," "Love," and the "Proceeding One." Therefore it seems that Baptism is valid if conferred in these names.
On the contrary, our Lord said (Matt. 28:19): "Going . . . teach ye all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost."
I answer that, Baptism receives its consecration from its form, according to Eph. 5:26: "Cleansing it by the laver of water in the word of life." And Augustine says (De Unico Baptismo iv) that "Baptism is consecrated by the words of the Gospel." Consequently the cause of Baptism needs to be expressed in the baptismal form. Now this cause is twofold; the principal cause from which it derives its virtue, and this is the Blessed Trinity; and the instrumental cause, viz. the minister who confers the sacrament outwardly. Wherefore both causes should be expressed in the form of Baptism. Now the minister is designated by the words, "I baptize thee"; and the principal cause in the words, "in the name of the Father, and of the Son, and of the Holy Ghost." Therefore this is the suitable form of Baptism: "I baptize thee in the name of the Father, and of the Son, and of the Holy Ghost."
Reply Obj. 1: Action is attributed to an instrument as to the immediate agent; but to the principal agent inasmuch as the instrument acts in virtue thereof. Consequently it is fitting that in the baptismal form the minister should be mentioned as performing the act of baptizing, in the words, "I baptize thee"; indeed, our Lord attributed to the ministers the act of baptizing, when He said: "Baptizing them," etc. But the principal cause is indicated as conferring the sacrament by His own power, in the words, "in the name of the Father, and of the Son, and of the Holy Ghost": for Christ does not baptize without the Father and the Holy Ghost.