From the Supplement, compiled after Aquinas’s death from his Commentary on the Sentences and transcribed here from the 1917 to 1922 printings. About the Supplement.
Text: Summa Theologiae, Supplement to the Third Part (Supplementum Tertiae Partis), transcribed from Internet Archive scans, translated by the Fathers of the English Dominican Province. The Supplement, compiled after Aquinas’s death from his earlier Commentary on the Sentences, in the same English Dominican translation as the Gutenberg Parts. Transcribed by Bibliotheca Catholica from the OCR of four Internet Archive scans of the pre-1931 printings (Questions 1 to 33 from the 1917 Washbourne and Benziger volume, 34 to 68 from the 1922 volume, 69 to 86 from the 1921 volume, and 87 to 99 from the 1922 Benziger volume), with OCR errors corrected and doubtful passages marked, not rewritten. 99 questions and 446 articles. The two appendices printed after Question 99 are not included. Sources, SHA-256 of each OCR file, and the method are in the source record. Rights: Public domain (US)
The Supplement is not a Project Gutenberg text. It is Bibliotheca Catholica’s transcription of public-domain scans at the Internet Archive; obvious OCR errors were corrected, and passages marked “OCR uncertain” could not be confidently corrected, so check them against the linked scan page.
Objection 1: It would seem that the character of Order does not presuppose the character of Baptism. For the character of Order makes a man a dispenser of the sacraments; while the character of Baptism makes him a recipient of them. Now active power does not necessarily presuppose passive power, for it can be without it, as in God. Therefore the character of Order does not necessarily presuppose the character of Baptism.
Obj. 2: Further, It may happen that a man is not baptized, and yet think with probability that he has been baptized. If therefore such a person present himself for Orders, he will not receive the character of Order, supposing the character of Order to presuppose the character of Baptism; and consequently whatever he does by way of consecration or absolution will be invalid, and the Church will be deceived therein, which is inadmissible.
On the contrary, Baptism is the door of the sacraments. Therefore since Order is a sacrament, it presupposes Baptism.
I answer that, No one can receive what he has not the power to receive. Now the character of Baptism gives a man the power to receive the other sacraments. Wherefore he that has not the baptismal character, can receive no other sacrament; and consequently the character of Order presupposes the character of Baptism.
Reply Obj. 1: In one who has active power of himself, the active does not presuppose the passive power; but in one who has active power from another, passive power, whereby he is enabled to receive the active power, is prerequisite to active power.
Reply Obj. 2: Such a man if he be ordained to the priesthood is not a priest, and he can neither consecrate, nor absolve in the tribunal of Penance. Wherefore according to the canons he must be baptized, and reordained (Extra. De Presbyt. non Bapt., cap. Si quis; cap. Veniens). And even though he be raised to the episcopate, those whom he ordains receive not the Order. Yet it may piously be believed that as regards the ultimate effects of the sacraments, the High Priest will supply the defect, and that He would not allow this to be so hidden as to endanger the Church.
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Also online, linked only: the same translation at New Advent and the Latin text at Corpus Thomisticum. Neither is copied here.