153. 11. Chastity cannot be ascribed to people who abstain from adulterous relationships only for various external reasons. Many people believe that chastity is simply abstinence from adultery physically, even though this is not chastity unless it is also at the same time abstinence in spirit. For a person's spirit - meaning here his mind in its affections and thoughts - is what makes him chaste or unchaste, chastity or unchasteness being in the body as a result of the spirit. For what the body is like depends entirely on the mind or spirit. It follows from this that people who abstain from adultery physically and not as a result of the spirit are not chaste, nor those who abstain from it in spirit for the sake of the body.

There are many reasons which cause a person to refrain from adulterous relationships physically, and also in spirit for the sake of the body. But still, a person who does not refrain from them physically as a result of the spirit is unchaste. For the Lord says:

(If anyone) looks at (another's) woman so as to lust for her, (he) has already committed adultery with her in his heart. (Matthew 5:28)

[2] We cannot list all the reasons for people's abstaining from adulterous relationships only physically, since these reasons vary according to the states of their marriage and also according to the states of their body.

For example, there are some who abstain from adulterous relationships because they are afraid of the civil law and its penalties; because they are afraid of losing reputation and thus respect; because they are afraid of diseases resulting from such relationships; because they are afraid of being railed at by their wives at home and of having no peace in their lives on account of it; because they are afraid the husband or a relative will take revenge; or because they are afraid of being beaten by the servants.

There are also some who abstain because they are too poor, or too stingy, or because they are too feeble owing either to illness, or to their abusing themselves, or to age, or to impotence.

There are some among them as well who, because they cannot or dare not do it physically, also for that reason condemn adultery in spirit and so speak in a moral fashion against it and in favor of marriage. But if these people do not renounce adultery in spirit and of the spirit in accordance with religion, they are still adulterers, for even though they do not do it physically, still they commit it in spirit. And after death, when they become spirits, they therefore speak openly in favor of it.

It is apparent from this that even an irreligious person can abstain from adulterous relationships as harmful, but that only a Christian can abstain from them as sins.

This now establishes the truth of the argument, that chastity cannot be ascribed to people who abstain from adulterous relationships only for various external reasons.