[quote=axolotl]St. Thomas Aquinas, Summa Theologica I q. 92 a. 1
"Woman is defective and misbegotten, for the active force in the male
seed tends to the production of a perfect likeness in the masculine sex;
while the production of woman comes from defect in the active force or
from some material indisposition, or even from some external influence,
such as that of a south wind, which is moist."
St. Thomas Aquinas, Summa Theologica II-II q.70 a.3
"The reliability of a person’s evidence is weakened, sometimes indeed on
account of some fault of his…; sometimes, without any fault on his
part, and this owing either to a defect in the reason, as in the case of
children, imbeciles and women, or to personal feeling…"
Always start by going to the source and looking for context. Especially with regard to Aquinas.
You would do well to read the whole thing.
Reply to Objection 1. As regards the individual nature, woman is defective and misbegotten, for the active force in the male seed tends to the production of a perfect likeness in the masculine sex; while the production of woman comes from defect in the active force or from some material indisposition, or even from some external influence; such as that of a south wind, which is moist, as the Philosopher observes (De Gener. Animal. iv, 2). On the other hand, as regards human nature in general, woman is not misbegotten, but is included in nature’s intention as directed to the work of generation. Now the general intention of nature depends on God, Who is the universal Author of nature. Therefore, in producing nature, God formed not only the male but also the female.
As a matter of science they only knew about sperm in his day. Not the egg. They assumed sperm was male and so they had to come up with some way of explaining where the woman came from. Aquinas is speaking of nature. Later however he says with regard to human nature she is not misbegotten. That is key.
There is a better article than the one below on the net but I can’t find it offhand but it will provide some further info.
A word must be said about the most widely used English version of the Summa Theologiae  which translates per respectum ad naturam particularem femina est aliquid deficiens et occasionatum thus: As regards the individual nature, woman is defective and misbegotten’.
Those unaware of the meaning of *natura particularis *might take this to mean that the individual nature of woman defective. As we have seen, the individual nature is the power of the male semen and while a female may not be what this semen intended to produce she is what Nature intends should be produced and as such is not defective.
Misbegotten' is an unhappy translation of *occasionatum. *In a more recent translation, it is given as *manque. *But since Aquinas had to hand William of Moerbeke's translation *orbatum, *which does mean *manque *and chose instead to use *occasionatum, *one wishesunintentionally produced’ had been used, for that is precisely what *occasionatum *means.