Saint Thomas Aquinas dealt with sexual morality as an aspect of the virtue of temperance, and incorporates Scripture throughout his account. In his Summa Theologiae he writes about chastity:
The word “chastity” is employed in two ways. First, properly; and thus it is a special virtue having a special matter, namely the concupiscences relating to venereal pleasures. Secondly, the word “chastity” is employed metaphorically: for just as a mingling of bodies conduces to venereal pleasure which is the proper matter of chastity and of lust its contrary vice, so too the spiritual union of the mind with certain things conduces to a pleasure which is the matter of a spiritual chastity metaphorically speaking, as well as of a spiritual fornication likewise metaphorically so called. For if the human mind delight in the spiritual union with that to which it behooves it to be united, namely God, and refrains from delighting in union with other things against the requirements of the order established by God, this may be called a spiritual chastity, according to 2 Cor. 11:2, “I have espoused you to one husband, that I may present you as a chaste virgin to Christ.” If, on the other hand, the mind be united to any other things whatsoever, against the prescription of the Divine order, it will be called spiritual fornication, according to Jer. 3:1, “But thou hast prostituted thyself to many lovers.” Taking chastity in this sense, it is a general virtue, because every virtue withdraws the human mind from delighting in a union with unlawful things. Nevertheless, the essence of this chastity consists principally in charity and the other theological virtues, whereby the human mind is united to God.
- Intercourse was banned on all Sundays
- All feast days
- 20 days before Christmas
- 40 days before Easter
- 20 days before Pentecost
- 3 or more days before receiving Communion (which at that time was offered only a few times a year).
These days amounted to approximately 40% of each year.