Whether the greatest pleasure occurs in generation by means of coition.
One asks further whether the greatest pleasure occurs in that generation that takes place by means of coition.
1. And it seems not. For pleasure results from the union of one thing suited to another, and sadness occurs from their separation. But in coition the semen, which is nearest to conversion, is separated. Therefore, there is more sadness in coition than pleasure.
2. In addition, each and every one takes more delight in preserving itself than in preserving another. Now, nutriment exists for the sake of preserving itself, whereas coition or generation exists for the sake of another. Therefore, there is more pleasure in nutrition than in coition, and therefore the greatest pleasure does not occur <in coition>.
3. And this is confirmed in this way. Pleasure follows sensation. But two senses operate in nutrition, namely, touch and taste, but in coition only one operates, namely, the touch from the contact of the penis with the vulva. Therefore, etc.
The Philosopher implies the opposite in the text. For he says that animals change their calls and are in motion at the time of coition and call out to one another, and many animals are solitary, and this is why, etc.
One must reply that each one rejoices at its proper operation, as it is said in the Ethics. For the just rejoices in just operations, and the temperate in temperate operations. But nature ordains nutriment for the sake of the preservation of the individual and the sexual act for the sake of the preservation of the species. And this is why nature joined the greatest pleasures to these operations, and the more it intends the preservation of the species than the preservation of the individual, the more it ordered the greater pleasure for the sex act than for the nutritive act [in opere venereo quam in opere nutritivae].
Moreover, pleasure results from the union of one suitable thing to another suitable thing. But semen is caused by the superfluity of aliment, which aliment is nevertheless suited for and close to conversion. Thus, when the semen courses through those members that are especially sensitive and nerve-filled, it causes the greatest pleasure. And in addition, the expulsion of what is superfluous is pleasurable, generation occurs through a superfluity, and semen arises from the superfluity of aliment. This is why its expulsion, which occurs in coition, is pleasurable.
1. On to the arguments. To the first, one must reply that if semen were suited for a part, and if it were on the way to conversion into a member, then its separation from that part into which it is convertible would not be pleasurable. But this is not the case in coition, when the semen courses through the nerve-filled members which are sufficiently restored and do not require its conversion. Thus its flow causes a certain titillation in the members, and it is not converted substantially into the members themselves, and this is why it can be expelled without pain.
2. To the second argument one must reply that although two senses concur in nutrition, nevertheless pleasure in coition is greater than that in nutrition. For although sensible pleasure may be greater in nutrition owing to the plurality of the senses [operative in it], nevertheless natural pleasure is greater in the sex act owing to the contact with that which is suited to it, or owing to the contact of those things which are more suited to it.
3. To the third, one must reply that nature is of two types: universal and particular. The preservation of the individual is the intention of the particular nature, and the preservation of the species is the intention of the universal nature. And this is why pleasure is greater in that act through which the species is preserved than in that act through which the individual is preserved.