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 compulsory consent makes a marriage, at least as regards the party who uses compulsion. For matrimony is a sign of a spiritual union. But spiritual union which is by charity may be with one who has not charity. Therefore marriage is possible with one who wills it not.
Obj. 2: Further, If she who was compelled consents afterwards, it will be a true marriage. But he who compelled her before is not bound by her consent. Therefore he was married to her by virtue of the consent he gave before.
On the contrary, Matrimony is an equiparant relation. Now a relation of that kind is equally in both terms. Therefore if there is an impediment on the part of one, there will be no marriage on the part of the other.
I answer that, Since marriage is a kind of relation, and a relation cannot arise in one of the terms without arising in the other, it follows that whatever is an impediment to matrimony in the one, is an impediment to matrimony in the other; since it is impossible for a man to be the husband of one who is not his wife, or for a woman to be a wife without a husband, just as it is impossible to be a mother without having a child. Hence it is a common saying that marriage is not lame.
Reply Obj. 1: Although the act of the lover can be directed to one who loves not, there can be no union between them, unless love be mutual. Wherefore the Philosopher says (Ethic, viii. 2) that friendship which consists in a kind of union requires a return of love.
Reply Obj. 2: Marriage does not result from the consent of her who was compelled before, except in so far as the other party's previous consent remains in force; wherefore if he were to withdraw his consent there would be no marriage.
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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.