I. To the Question

7. I reply.

Someone who said that filiation belongs precisely to the supposit and not to the nature could easily say that Christ is not an adoptive son, because this relation does not belong to the supposit in itself.

8. But by saying that filiation is founded on a nature naturally like the one who generates, then adoptive sonship will be founded on a nature that (as image of the creator) is similar to the creator by natural likeness, and also by likeness of grace, whereby the nature is able, as intellectual nature, to attain to the inheritance of adoption. For the term ‘adoption’ has been borrowed from the jurists, so that an adoptive son is said to be he who is not naturally generated by a certain person and does not have, by natural generation, the right of succeeding to the inheritance, but who is by grace preordained to have the right of succeeding. Thus three things come together here: foreignness to natural generation, the grace that is the gratuitous will of the one adopting, and the good to which the one adopted is ordained by grace, namely the inheritance that he has, from adoption, the right of succession to. But it is plain that these are not found together in Christ as to his divine nature, because he is by divine generation a natural heir to eternal life; neither are they found together in him as to his human nature, because he was not foreign as to his generation in that nature, since he was innocent.Because, presumably, he would thus not be estranged by any sin from union with God. ⁹⁰

9. On the contrary: if this ‘foreignness’ is understood to be found only in possession of sin, then Mary was not an adoptive daughter (if she never contracted original sin), which however is false.

10. If it be said that she would have contracted original sin insofar as she came to be by natural generation (that is, through the idea of seed), while Christ, as Christ, lacked the source in natural generation for contracting sin - then Adam, at any rate in the state of innocence, would not have been an adoptive son of God, because he did not contract sin and lacked a ground for then contracting it, since he was created or produced without the idea of seed; the angels too would not be adoptive sons, because they were always innocent.

11. Besides, it is plain that there is no need that, in the case of human adoption, the one adopted be foreign - that is an enemy - whether by his own act or by that of his parents, because someone who is an enemy in one or other of these ways is not typically adopted, but rather he is who is loved in one or other of these ways. So the foreignness is sufficient which comes from lack of right to the inheritance of the one adopting, and that because of lack of natural generation. Now Christ in his temporal generation did not have a right to eternal inheritance; therefore he had the foreignness necessary for being adopted; and it is plain that, as son of man, he possesses the right by grace, and so is adopted.

12. Someone who does not accept this reasoning [n.11] can say that, in the case of an adopted son, the sort of foreignness required is that at the moment of natural generation he not have the right of inheritance, so that he has natural being first and is foreign prior to adoption. Christ was never without grace, and so he was not adopted.

13. But this reasoning [n.12] does not seem sufficient, for then the angel, if he was created in grace, would not have been adopted nor be an adopted son of God; therefore priority of nature is sufficient, namely that an adopted person does not, in the first moment of nature when he is generated or created, have the right of inheritance from that generation or creation, but has it rather from grace in the second moment. So it is in the case at hand: for Christ’s human nature naturally brought the process of generation to completion first, but it was, prior to habitual grace existing in it, united to the Word (III d.2 a.2 q.2, nn.88-91).

14. If this response is not agreed to, one could say finally that the foreignness required, whether in a prior instant of time or nature, is not of the sort that some right conferring inheritance need accompany the natural generation as a deserving disposition for it; but a deserving grace whereby Christ’s soul had a right to the inheritance did here accompany temporal generation.

15. And if it be objected that the grace accompanied it, not in the first moment of nature but in the second, and so Christ was foreign and had foreignness in the first moment, for his soul lacked the right that was conferred in the second moment - see the response in III d.3 nn.46-49 about whether Mary was a natural daughter of Adam before she was justified.