Question Three: Concerning Consummated Lust According to Nature

Besides the vice against nature, which altogether impedes the due end itself of venereal pleasure, namely generation, there are six principal species of complete lust according to nature, from which generation, namely, can follow: simple fornication, stuprum, raptus, adultery, incest, sacrilege.

For sins differ in species according to objects morally diverse, namely those which include a diverse repugnance to right reason. But in lust according to nature, on the part of the proper object, there can be six diverse repugnances to right reason. Therefore.

The minor is proved: moral deformity and repugnance to right reason can be by comparison with the partner, who:

1. either is merely unmarried and consenting, not qualified, so that there is deformity only on the part of the end, insofar as the due education of offspring is impeded, and then it is simple fornication, which is so called because it is simple lust against chastity alone;

2. or is a virgin under the power of her father, and then it is stuprum, even if violence is not inflicted upon the person;

3. or is one to whom violence is inflicted, and then it is raptus;

4. or is one joined to another, and then it is adultery;

5. or is one too closely related, to whom due honor is not preserved, and then it is incest;

6. or is one dedicated to God by vow, and then it is carnal sacrilege.

Nor should you say that these are not diverse species of lust, because they do not repugn to chastity in a special and diverse way but to other virtues: justice, religion, piety, and so forth. For there is also a special repugnance to chastity, and concupiscence is shown to be more inordinate, when someone tends so vehemently to lust that on account of it he does not fear also to sin against justice, religion, or piety. Namely, the species of sin is primarily from the end.

Concerning these diverse sins we must now speak in particular.