The Greeks, however, do not attribute the act of baptizing to the minister, in order to avoid the error of those who in the past ascribed the baptismal power to the baptizers, saying (1 Cor. 1:12): "I am of Paul . . . and I of Cephas." Wherefore they use the form: "May the servant of Christ, N . . ., be baptized, in the name of the Father," etc. And since the action performed by the minister is expressed with the invocation of the Trinity, the sacrament is validly conferred. As to the addition of "Ego" in our form, it is not essential; but it is added in order to lay greater stress on the intention.
Reply Obj. 2: Since a man may be washed with water for several reasons, the purpose for which it is done must be expressed by the words of the form. And this is not done by saying: "In the name of the Father, and of the Son, and of the Holy Ghost"; because we are bound to do all things in that Name (Col. 3:17). Wherefore unless the act of baptizing be expressed, either as we do, or as the Greeks do, the sacrament is not valid; according to the decretal of Alexander III: "If anyone dip a child thrice in the water in the name of the Father, and of the Son, and of the Holy Ghost, Amen, without saying, I baptize thee in the name of the Father, and of the Son, and of the Holy Ghost, Amen, the child is not baptized."
Reply Obj. 3: The words which are uttered in the sacramental forms, are said not merely for the purpose of signification, but also for the purpose of efficiency, inasmuch as they derive efficacy from that Word, by Whom "all things were made." Consequently they are becomingly addressed not only to men, but also to insensible creatures; for instance, when we say: "I exorcize thee, creature salt" (Roman Ritual).
Reply Obj. 4: Several cannot baptize one at the same time: because an action is multiplied according to the number of the agents, if it be done perfectly by each. So that if two were to combine, of whom one were mute, and unable to utter the words, and the other were without hands, and unable to perform the action, they could not both baptize at the same time, one saying the words and the other performing the action.
On the other hand, in a case of necessity, several could be baptized at the same time; for no single one of them would receive more than one baptism. But it would be necessary, in that case, to say: "I baptize ye." Nor would this be a change of form, because "ye" is the same as "thee and thee." Whereas "we" does not mean "I and I," but "I and thou"; so that this would be a change of form.
Likewise it would be a change of form to say, "I baptize myself": consequently no one can baptize himself. For this reason did Christ choose to be baptized by John (Extra, De Baptismo et ejus effectu, cap. Debitum).
Reply Obj. 5: Although Christ's Passion is the principal cause as compared to the minister, yet it is an instrumental cause as compared to the Blessed Trinity. For this reason the Trinity is mentioned rather than Christ's Passion.
Reply Obj. 6: Although there are three personal names of the three Persons, there is but one essential name. Now the Divine power which works in Baptism, pertains to the Essence; and therefore we say, "in the name," and not, "in the names."
Reply Obj. 7: Just as water is used in Baptism, because it is more commonly employed in washing, so for the purpose of designating the three Persons, in the form of Baptism, those names are chosen, which are generally used, in a particular language, to signify the Persons. Nor is the sacrament valid if conferred in any other names. _______________________
SIXTH ARTICLE [III, Q. 66, Art. 6]