B. The Application of the Aforesaid to the Question

74. Hereby is the answer clear by application to the question -

The contract, indeed, of matrimony [n.72] was instituted by God, Genesis 2.24, “This now is bone of my bones,” 1.28, “Increase and multiply;” and after the Fall 3.16, “I will multiply your conceptions and your sorrows,” said God to Eve; and Genesis 9.1, “Increase and multiply,” he said to Noah and his family. And the institution is by way of affirmative precept, so that it is always binding but not at all times but for time of necessity - not only at the beginning, but it seems to obligate still in the same way if a like paucity were for some reason to come about, as from war or plague or disaster and the like. And this proves how the contract was instituted by God through divine and positive law, and by his similarly impressing the law of nature on the hearts of men, to which law of nature does this contract belong, if not completely as known of necessity, yet as secondarily consonant with it.

75. The second part, namely indissoluble obligation [n.71], God instituted by his positive law, Genesis 2.24, “He will cleave to his wife” - ‘will cleave’, I say, not ‘momentarily accept’. God also instituted it by impress of the law of nature, not only as to things that are known evidently from the same law but as to those that are evidently consonant with that law. And that he did so institute it is proved at the beginning of the third man conclusion [nn.39-43]. Now this second precept has the force of a negative precept, because it obligates always and at all times, unless a special dispensation be made by the Legislator, as will be said below in d.33 nn.15-21.

76. He instituted also the third part, namely the sacrament of matrimony [n.73], as was said in the fourth main conclusion [nn.47-50].

77. But there is here a doubt when the reasonableness of the contract of matrimony, and of the obligation, and the divine institution of it are obtained from all these conclusions, and from the solution, only because of this end, namely to procreate offspring to be duly educated. And this institution is said to have been instituted as a duty. But, besides this, matrimony is also said to have been instituted as a remedy, namely for avoiding incontinence after the Fall. How, first, is the honorableness of the contract or of the obligation obtained in this way? Or how is there divine institution or approval of it for this end?

78. I reply: it does not appear an easy thing that anyone should, according to right reason, use this act precisely for pleasure; indeed, the opposite seems more consonant with reason. Therefore, this is more something to be tolerated; because nothing laudable seems to be found in the act save procreation of offspring. Natural reason too does not seem to establish any honorableness in the act, nor consequently in the obligation or in the mutual obligatory contract for the act, nor consequently to establish that the Legislator should rightly approve or institute such contract or obligation.

79. What then if it be said that someone who wants to use his body for this delight, so that he not use it unjustly with someone not his own, can make exchange of his body with the body of another which he may justly use as his own, and then this giving is honorable because of this justice? Also, on the presupposition that such an end is licit, it will not then be necessary that, in order to use it licitly, he use it for such act by the license of God, because (as was said when excluding the reason for the third main conclusion [n.46]), God committed to each one his own self and his own property, wherein he did not obligate him specifically to himself. If this answer not satisfy, nor is justice for this act more praiseworthy than a just exchange is for another act that would not be praiseworthy (as an exchange to use something else for a similar use elsewhere), at least can, conversely, recourse be had here to a divine institution that is not based on the praiseworthiness of an act for an end other than propagation, but based on infirmity after the Fall for avoiding a greater evil. And, having allowed this indulgence, he instituted a contract ordained for it - if not by the impress of the law of nature, at least by positive law; and this both as to contract and as to obligation.

80. But it is difficult to find the ‘when’ in between as concerns the contract for the first end, because never in the Old Testament is there found a contract prescribed or praised save for procreation of offspring; for always the divine command is for this, “Increase,” which is only by propagating. At least in the New Testament we are informed that this contract is indulged for another end, namely avoidance of fornication, I Corinthians 7.6, “But this I say according to indulgence etc.,” and it is likely that such an obligation would not first have been made in the New Law, but from the beginning of human law.

81. So then, from the first conclusions is obtained the result about the institution of the contract of matrimony, and about obligation in order to procreate offspring, and also about the institution of the sacrament accompanying the contract. But the institution of this contract for avoiding fornication is not so obtained by natural reason, indeed scarcely as something permitted by divine institution. Justice there as to indissolubility, however, and the sacrament accompanying the contract, are made clear in the same way as previously about matrimony instituted for the first end [nn.7-30].

82. To the first argument [n.3] the answer is plain from the third conclusion [n.9], that Adam pronounced as herald the words “This is bone of my bones etc.,” as is manifestly expressed by Christ in Matthew 19.4-6, when speaking about God who made them male and female he said, “Wherefore a man will cleave etc.” For if Adam had instituted matrimony and had not just been the herald and minister of God who did the instituting, Adam could have revoked matrimony - which is not true.

83. As to the second [n.4], I believe that no one inferior to God can change anything in what is essential to the contract of matrimony (on the presupposition of suitable matter), or about matrimony when a firm and ratified contract has been made. But the Church does sometimes well make changes as to fitting and unfitting matter, by ordaining what matters should and what should not make a contract; for so does the Church do about the matter of penitence, subjecting this man to this priest as subject to him and not to another; but about the virtue or sacrament of penitence the Church cannot change anything.