b. Proof of the Second Main Conclusion

32. For the proof of the second main conclusion [n.8], let this be the first prior conclusion: it is expedient that that indissoluble obligation arise from the act of will of the persons obligated.

33. The proof of this is that the obligation will arise either in this way or by imposition of a superior, namely the legislator. Not the second, because no law ordains or determines this woman to this man or conversely; therefore, the first. And a fitting reason is that the first is more useful and more agreeable to natural reason, because, from the fact that the obligation should be indissoluble, it is expedient that the manner in which it is done be agreeable to the indissolubility of it. But if they were compelled by a legislator to be joined together, they would be less mutually pleasing to each other, and so there would be greater occasion for future dissension; for as is said in Gratian, Decretum, p.2 cause 30 q.3 ch.4, “What someone does not choose, assuredly he does not love; but what he does not love, he easily despises.”

34. Let the second conclusion be this, that it is honorable that, in a contract of mutual giving, male and female transfer mutually to each other the power of their bodies for this end in their perpetuity.

35. This is plain from the preceding conclusion [n.32], once the reason for a contract of mutual donation is seen. For a ‘con-tract’ is said to be as it were a drawing together of two wills to each other or of two who are obligating each other; and consequently it necessarily requires acts of will that agree in a mutual transfer, as in the case of other exchanges or sellings (taking ‘selling’ commonly). Nor does this suffice, but it is necessary for these acts to be expressed by certain signs, otherwise there would be no certainly for either about the act of will of the other. Also, neither wants to make a transfer to the other save to the extent each conceives the other to want to make a transfer to them.

36. So if, from the preceding conclusion [n.32], it is expedient for them to be obligated through their own wills, and not without signs (expressing or expressed), then it is expedient that there be a contract there from which the obligation arises. But this contract can only be one of mutual giving or interchange (which is the same thing) of power over their bodies for this end in their perpetuity; because power over one’s body, which is one’s own power, is not transferred by anyone to another save by act of will, because by that act he was lord and ceases to be lord and makes another to be lord. And consequently, the right that the other acquires over this one’s body when it is transferred to him is by an act of will freely transferring it - and this along with an extrinsic evident sign from which is obtained the idea of the aforesaid contract. And this contract is called ‘I give if you give’ or ‘I give so that you may give’.

37. This mutual transfer of lordship of bodies is plain according to the rule of the Apostle in I Corinthians 7.4, “The woman does not have power of her own body but the man; and the man does not have power of his own body but the woman;” and thus does each have power over the body of the other and over their own by reason of the mutual giving and the mutual contract - and this as to the act of the body that regards procreation of offspring.