The Catechism of St. Thomas Aquinas
THE TENTH (NINTH) COMMANDMENT: “Thou Shalt Not Covet Thy Neighbor’s Wife.”
Because of the corruption which resulted from the Fall, none has been free from concupiscence except Christ and the glorious Virgin. And wherever there is concupiscence, there is either venial or mortal sin, provided that it is allowed to dominate the reason. Hence the precept is not, let sin not be; for it is written: “I know that there dwelleth not in me [that is to say, in my flesh] that which is good.”
First of all, sin rules in the flesh when, by giving consent to it, concupiscence reigns in the heart. And, therefore, St. Paul adds “so as to obey the lusts thereof” to the words: “Let not sin reign in your mortal body.” Accordingly the Lord says: “Whosoever shall look on a woman to lust after her, hath already committed adultery with her in his heart.” For with God the intention is taken for the act.
Secondly, sin rules in the flesh when the concupiscence of our heart is expressed in words: “Out of the abundance of the heart the mouth speaketh.” And again: “Let no evil speech proceed from your mouth.” Therefore, one is not without sin who composes frivolous songs. Even the philosophers so thought, and poets who wrote amatory verses were sent into exile. Lastly, sin rules in the flesh when at the behest of desire the members are made to serve iniquity: “As you have yielded your members to serve uncleanness and iniquity unto iniquity.” These, therefore, are the progressive steps of concupiscence.
WAYS TO OVERCOME CONCUPISCENCE
We must realize that the avoidance of concupiscence demands much labor, for it is based on something within us. It is as hard as trying to capture an enemy in one’s own household. However, this desire can be overcome in four ways.
Firstly, by fleeing the external occasions such as, for instance, bad company; and in fact whatever may be an occasion for this sin: “Gaze not upon a maiden lest her beauty be a stumbling-block to thee. . . . Look not around about thee in the ways of the city, nor wander up and down in the streets thereof. Turn away thy face from a woman dressed up, and gaze not about upon another’s beauty. For many have perished by the beauty of a woman, and hereby lust is enkindled as a fire.” And again: “Can a man hide fire in his bosom, and his garments not burn?” And thus Lot was commanded to flee, “neither stay thou in all the country about.”
The second way is by not giving an opening to thoughts which of themselves are the occasion of lustful desires. And this must be done by mortification of the flesh: “I chastise my body, and bring it into subjection.” The third way is perseverance in prayer: “Unless the Lord build the house, they labor in vain who build it.” And also: “I knew that I could not otherwise be
continent, except God gave it.” Again: “This kind is not cast out save by prayer and fasting.” All this is not unlike to a fight between two persons, one of whom you desire to win, the other to lose. You must sustain the one and withdraw all support from the other. So also between the spirit and the flesh there is a continual combat. Now, if you wish the spirit to win, you must assist it by prayer, and likewise you must resist the flesh by such means as fasting; for by fasting the flesh is weakened.
The fourth way is to keep oneself busy with wholesome occupations: “Idleness hath taught much evil.” Again: “This was the iniquity of Sodom thy sister, pride, fullness of bread, and abundance, and the idleness of her.” St. Jerome says: “Be always busy in doing something good, so that the devil may find you ever occupied.” Now, study of the Scriptures is the best of all occupations, as St. Jerome tells us: “Love to study the Scriptures and you will not love the vices of the flesh.”
1. John, ii. 16.
2. The text of Exodus xx. 17, which contains the Ninth and Tenth Commandments, reads as follows: “Thou shalt not covet thy neighbor’s house: neither shalt thou desire his wife, nor his servant, nor his hand-maid, nor his ox, nor his ass, nor anything that is his.”
3. Ps. cxi. 3.
4. “He [the pastor] will show how these two Commandments are dissimilar; how one covetousness looks only to utility and interest (the tenth), the other to unlawful desire and criminal pleasure (the ninth). If one covets a field or house, he acts out of desire for gain or utility, while he who covets another man’s wife yields to a desire for criminal pleasure rather than monetary gain” (“Roman Catechism,” “loc. cit., 2).
5. “Concupiscence, the fuel of sin, which originated in sin, is always present in our fallen nature: from it we know that we are born in sin, and, therefore, we suppliantly fly to Him who alone can efface the sordid stains of sin” (“Roman Catechism,” “loc. cit.,” 5).
6. Rom., vii. 18.
7. “lbid.,” vi. 12.
8. Matt., v. 28.
9. Matt., xii. 34.
10. Eph., iv. 29.
11. Rom., vi. 19.
12. Ecclus., ix. 5-9.
13. Prov., vi. 27.
14. Gen., xix. 17.
15. Cor., ix. 27.
16. Ps. cxxvi. 1.
17. Wis., viii. 21.
18. Matt., xvii. 20.
19. Ecclus., xxxiii. 29.
20. Ezech., xvi. 49.
21. “Ad Paulin.”