2. Rejection of the Opinion

19. But against this [n.16] there is first a fourfold argument about other mothers:

[i] Because forms of the same species are followed by natural powers of the same species; but male and female are of the same species, Metaphysics 10.9.1058a29-34, b21-24; so their forms are followed by a power of the same idea; therefore if the form of one is naturally followed by an active vegetative power, likewise too is the other’s. And this reason is confirmed, because otherwise the vegetative power of the latter and the former would differ as active and passive differ, and thus they would be powers of an altogether different idea.

20. [ii] Further, the father naturally loves his son more than the son the father, just as “each naturally more loves his work than conversely,” from Ethics 8.12.1161b24-26, 9.7.1167b34-35; and this argument holds because of the fact that the benefactor is more affected toward the benefitted than conversely; but the mother loves her son more than the father does, as is plain from Aristotle in Ethics 8.14.1161b26-30, 9.7.1168a24-26; therefore it seems that her son is in some way her work.

21. [iii] Further, a son is sometimes more like his mother than like his father; so there is in the mother too some active power. The proof of the consequence is that “an agent aims to make the effect like itself” [Generation and Corruption 1.7.324a9-11], so that the effect is only made like something because of some action.

22. It is said [Aquinas] that the seed of the mother principally tends to make the offspring like the father and, secondly, that because of lack of obedience in the matter the seed of the mother fails of what it tends to do and does what it can - and thus, since alteration does not change to anything at all but to the opposite, the likeness is made to the opposite and so to the mother.

23. Against this: in that case a hot thing that is impeded and unable, because of the impediment, to make the effect perfectly like itself, will make it like the cold - and this seems impossible, because the impeded hot will only not make the effect like itself; therefore if the effect is made like the cold, this is from another agent, not merely from the impeded hot. So, in the issue at hand, from an impediment resisting the active power of the father there is only got this negation, that the offspring is not made like the father; however the offspring will only be made like another from some other active cause - and if this be thus granted in the issue at hand on the part of the mother, the intended conclusion is obtained.

24. Further, to say that ‘the mother is only a sort of vessel in which, as in a place suitable for generation, the offspring is generated, and generated from something of her as from matter’, does not seem to give more to the mother than to the earth in the generation of a mineral (if the mineral is generated from the earth and the earth itself -containing the something that is corrupted - is a fitting place for generation of such a body); nay rather, it does not seem to give to the mother more than is given to a human being in respect of the generation of a worm because the worm is generated from some moisture that has become putrid, and this in a place fitting for its generation; and then the human being would lack nothing in being the mother of the worm save that the worm is not of the same species. But this perhaps does not take away [the human being the mother] if a horse may be called the father of a mule and an ass the mother.

25. [iv] Further, this opinion [n.16] in the issue at hand about this Mother [sc. Mary] is rejected by the remark of Damascene ch.46, “The Holy Spirit came over her.. .giving her a susceptive power for the deity of the Word as well as a generative power at the same time;” but if Mary were only a passive principle there would seem no reason that the Holy Spirit should join to the susceptive power a generative power at the same time.