Whether trine immersion is essential to Baptism?

❌ Objection 1 : It seems that trine immersion is essential to Baptism. For Augustine says in a sermon on the Symbol, addressed to the Neophytes: "Rightly were you dipped three times, since you were baptized in the name of the Trinity. Rightly were you dipped three times, because you were baptized in the name of Jesus Christ, Who on the third day rose again from the dead. For that thrice repeated immersion reproduces the burial of the Lord by which you were buried with Christ in Baptism." Now both seem to be essential to Baptism, namely, that in Baptism the Trinity of Persons should be signified, and that we should be conformed to Christ's burial. Therefore it seems that trine immersion is essential to Baptism.

❌ Objection 2 : Further, the sacraments derive their efficacy from Christ's mandate. But trine immersion was commanded by Christ: for Pope Pelagius II wrote to Bishop Gaudentius: "The Gospel precept given by our Lord God Himself, our Saviour Jesus Christ, admonishes us to confer the sacrament of Baptism to each one in the name of the Trinity and also with trine immersion." Therefore, just as it is essential to Baptism to call on the name of the Trinity, so is it essential to baptize by trine immersion.

❌ Objection 3 : Further, if trine immersion be not essential to Baptism, it follows that the sacrament of Baptism is conferred at the first immersion; so that if a second or third immersion be added, it seems that Baptism is conferred a second or third time. which is absurd. Therefore one immersion does not suffice for the sacrament of Baptism, and trine immersion is essential thereto.