Thomas Aquinas

“ 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. ”

“ 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. ”

“ 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." ”

“ Venereal pleasures are more impetuous, and are more oppressive on the reason than the pleasures of the palate: and therefore they are in greater need of chastisement and restraint, since if one consent to them this increases the force of concupiscence and weakens the strength of the mind. ”

“ 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. ”

“ Among the vices of intemperance, venereal sins are most deserving of reproach, both on account of the insubordination of the genital organs, and because by these sins especially, the reason is absorbed. ”