On the contrary, Dionysius says (Eccl. Hier. ii) that "the priests taking the baptized hand him over to his sponsor and guide."
I answer that, The spiritual regeneration, which takes place in Baptism, is in a certain manner likened to carnal generation: wherefore it is written (1 Pet. 2:2): "As new-born babes, endowed with reason desire milk [Vulg.: 'desire reasonable milk'] without guile." Now, in carnal generation the new-born child needs nourishment and guidance: wherefore, in spiritual generation also, someone is needed to undertake the office of nurse and tutor by forming and instructing one who is yet a novice in the Faith, concerning things pertaining to Christian faith and mode of life, which the clergy have not the leisure to do through being busy with watching over the people generally: because little children and novices need more than ordinary care. Consequently someone is needed to receive the baptized from the sacred font as though for the purpose of instructing and guiding them. It is to this that Dionysius refers (Eccl. Hier. xi) saying: "It occurred to our heavenly guides," i.e. the Apostles, "and they decided, that infants should be taken charge of thus: that the parents of the child should hand it over to some instructor versed in holy things, who would thenceforth take charge of the child, and be to it a spiritual father and a guide in the road of salvation."
Reply Obj. 1: Christ was baptized not that He might be regenerated, but that He might regenerate others: wherefore after His Baptism He needed no tutor like other children.
Reply Obj. 2: In carnal generation nothing is essential besides a father and a mother: yet to ease the latter in her travail, there is need for a midwife; and for the child to be suitably brought up there is need for a nurse and a tutor: while their place is taken in Baptism by him who raises the child from the sacred font. Consequently this is not essential to the sacrament, and in a case of necessity one alone can baptize with water.
Reply Obj. 3: It is not on account of bodily weakness that the baptized is raised from the sacred font by the godparent, but on account of spiritual weakness, as stated above. _______________________
EIGHTH ARTICLE [III, Q. 67, Art. 8]
Whether He Who Raises Anyone from the Sacred Font Is Bound to
Instruct Him?
Objection 1: It seems that he who raises anyone from the sacred font is not bound to instruct him. For none but those who are themselves instructed can give instruction. But even the uneducated and ill-instructed are allowed to raise people from the sacred font. Therefore he who raises a baptized person from the font is not bound to instruct him.
Obj. 2: Further, a son is instructed by his father better than by a stranger: for, as the Philosopher says (Ethic. viii), a son receives from his father, "being, food, and education." If, therefore, godparents are bound to instruct their godchildren, it would be fitting for the carnal father, rather than another, to be the godparent of his own child. And yet this seems to be forbidden, as may be seen in the Decretals (xxx, qu. 1, Cap. Pervenit and Dictum est).
Obj. 3: Further, it is better for several to instruct than for one only. If, therefore, godparents are bound to instruct their godchildren, it would be better to have several godparents than only one. Yet this is forbidden in a decree of Pope Leo, who says: "A child should not have more than one godparent, be this a man or a woman."