Of the remaining three, it is clear that Baptism which is a spiritual regeneration, comes first; then Confirmation, which is ordained to the formal perfection of power; and after these the Eucharist which is ordained to final perfection.
Reply Obj. 1: Matrimony as ordained to natural life is a function of nature. But in so far as it has something spiritual it is a sacrament. And because it has the least amount of spirituality it is placed last.
Reply Obj. 2: For a thing to be an agent it must first of all be perfect in itself. Wherefore those sacraments by which a man is perfected in himself, are placed before the sacrament of order, in which a man is made a perfecter of others.
Reply Obj. 3: Nourishment both precedes growth, as its cause; and follows it, as maintaining the perfection of size and power in man. Consequently, the Eucharist can be placed before Confirmation, as Dionysius places it (Eccl. Hier. iii, iv), and can be placed after it, as the Master does (iv, 2, 8).
Reply Obj. 4: This argument would hold if Penance were required of necessity as a preparation to the Eucharist. But this is not true: for if anyone be without mortal sin, he does not need Penance in order to receive the Eucharist. Thus it is clear that Penance is an accidental preparation to the Eucharist, that is to say, sin being supposed. Wherefore it is written in the last chapter of the second Book of Paralipomenon (cf. 2 Paral 33:18): "Thou, O Lord of the righteous, didst not impose penance on righteous men." [*The words quoted are from the apocryphal Prayer of Manasses, which, before the Council of Trent, was to be found inserted in some Latin copies of the Bible.]
Reply Obj. 5: Extreme Unction, for this very reason, is given the last place among those sacraments which are ordained to the perfection of the individual. _______________________
THIRD ARTICLE [III, Q. 65, Art. 3]
Whether the Eucharist Is the Greatest of the Sacraments?
Objection 1: It seems that the Eucharist is not the principal of the sacraments. For the common good is of more account than the good of the individual (1 Ethic. ii). But Matrimony is ordained to the common good of the human race by means of generation: whereas the sacrament of the Eucharist is ordained to the private good of the recipient. Therefore it is not the greatest of the sacraments.
Obj. 2: Further, those sacraments, seemingly, are greater, which are conferred by a greater minister. But the sacraments of Confirmation and order are conferred by a bishop only, who is a greater minister than a mere minister such as a priest, by whom the sacraments of the Eucharist is conferred. Therefore those sacraments are greater.