Whether the mother or the father is more responsible for an obstacle to generation.
Perhaps it happens to certain men," etc. Here a determination is made concerning an obstacle to generation. A question is first raised concerning this issue in the tenth book, namely, whether the mother or the father is more responsible for an obstacle to generation.
1. And it seems that it is the father. Because the more noble a thing is, the more things are necessary for its operation. But the male is nobler than the female, and therefore more things are required for its activity. But that which requires more things can also be impeded by more things; therefore, etc.
2. Moreover, the fetus has various configurations and lineations. But the man's sperm is more viscous and globular, and as a result it is more antithetical to a linear shape. Therefore, etc.
3. Moreover, sperm is a superfluity of the nutrimental moisture. But the male has less of this moisture than the female, and there is less of it in thin people than in fat people, and women have more fat than men, and therefore, etc.
But the Philosopher says the opposite.
One must reply to this that more obstacles are owing to the mother than the father, because the man is the cause of generation through the separation of his semen, whereas the woman is a cause of generation to the extent that she condenses and leavens the [separated] sperm and protects the fetus. And this is why she can impede generation in several ways.
Moreover, an appropriate disposition of the womb is required for the production of a fetus. But the womb is a noble member, and this is why it is very prone to injury. It is a nerve-filled member, and as a result it frequently suffers spasms, which are an affliction of the nerves. Moreover, it often abounds in bad humors, and this is why sometimes it suffers from wind, because when bad matter is concentrated in some member, then nature returns to that place to expel that matter utterly, if it can. And if it cannot, it dissolves the matter into windy vapors. The infirmity comes to an end if the pathways for expulsion are made available for these vapors. If, however, the pathways are not made available for them, then they cause great distress and are very much in motion. For it is the same for vapors that are shut up in the belly of the earth and are unable to come forth. These vapors cause an earthquake as a result of their enclosure and their agitation, but, if an exit is available for them, they do not cause an earthquake but rather pass forth into the wind in the air, or into something else. It is just this way for vapors enclosed in some member, for they then cause giddiness or something else. Thus there are many causes stemming from the man that are responsible for an inability to become pregnant: It can be either from a defect in the semenif it is too hot, or too liquid, or too coldor from a defect in the generative members, such as when the penis is too long or too short or cannot become erect or because the testicles are cold. And there are similar and even more causes stemming from the woman, because she not only attends to the semen but also conserves it, and there can be a defect stemming from conserving it. Therefore, etc.
1. To the first argument one must reply that although several things are required for the completed action of the man, nevertheless the woman requires many more for generation, and therefore, etc.
2. To the second argument one should reply that two things impede the semen: too much moisture or too much dryness, whereas a globular semen occupies the mean, and therefore, etc.
3. To the third argument one should reply that although the woman has more superfluous moisture, she nevertheless does not have more spermatic moisture. An indication of this is that a man can impregnate more frequently than a woman can be impregnated; therefore, etc.