The Catechism of St. Thomas Aquinas

THE NINTH (TENTH) COMMANDMENT:[1] “Thou shalt Not Covet Thy Neighbor’s Goods.”


“Thou shalt not covet thy neighbor’s goods.” There is this difference between the divine and the human laws that human law judges only deeds and words, whereas the divine law judges also thoughts. The reason is because human laws are made by men who see things only exteriorly, but the divine law is from God, who sees both external things and the very interior of men. “Thou art the God of my heart.”[2] And again: “Man seeth those things that appear, but the Lord beholdeth the heart.”[3] Therefore, having considered those Commandments which concern words and deeds, we now treat of the Commandments about thoughts. For with God the intention is taken for the deed, and thus the words, “Thou shalt not covet,” mean to include not only the taking by act, but also the intention to take. Therefore, it says: “Thou shalt not even covet thy neighbor’s goods.” There are a number of reasons for this.

The first reason for the Commandment is that man’s desire has no limits, because desire itself is boundless. But he who is wise will aim at some particular end, for no one should have aimless desires: “A covetous man shall not be satisfied with money.”[4] But the desires of man are never satisfied, because the heart of man is made for God. Thus, says St. Augustine: “Thou hast made us for Thee, O Lord, and our heart is restless until it rests in Thee.”[5] Nothing, therefore, less than God can satisfy the human heart: “Who satisfieth thy desire with good things.”[6]

The second reason is that covetousness destroys peace of heart, which is indeed highly delightful. The covetous man is ever solicitous to acquire what he lacks, and to hold that which he has: “The fullness of the rich will not suffer him to sleep.”[7] “For where thy treasure is, there is thy heart also.”[8] It was for this, says St. Gregory, that Christ compared riches to thorns.[9]

Thirdly, covetousness in a man of wealth renders his riches useless both to himself and to others, because he desires only to hold on to them: “Riches are not comely for a covetous man and a niggard.”[10] The fourth reason is that it destroys the equality of justice: “Neither shalt thou take bribes, which even blind the wise, and pervert the words of the just.”[11] And again: “He that loveth gold shall not be justified.”[12] The fifth reason is that it destroys the love of God and neighbor, for says St. Augustine: “The more one loves, the less one covets,” and also the more one covets, the less one loves. “Nor despise thy dear brother for the sake of gold.”[13] And just as “No man can serve two masters,” so neither can he serve “God and mammon.”[14]

Finally, covetousness produces all kinds of wickedness. It is “the root of all evil,” says St. Paul, and when this root is implanted in the heart it brings forth murder and theft and all kinds of evil. “They that will become rich, fall into temptation, and into the snare of the devil, and into many unprofitable and hurtful desires which drown men in destruction and perdition. For the desire of money is the root of all evil.”[15] And note, furthermore, that covetousness is a mortal sin when one covets one’s neighbor’s goods without reason; and even if there be a reason, it is a venial sin.[16]


1. St. Thomas places the Tenth Commandment (in the present traditional enumeration) before the Ninth. The Tenth Commandment is wider in extension than the Ninth, which is specific. The “Roman Catechism” (“Ninth and Tenth Commandments” 1) treats both the Ninth and Tenth Commandments together, and remarks that “what is commanded in these two precepts amounts to this, that to observe the preceding Commandments we must be particularly careful not to covet. For he who does not covet, being content with what he has, will not desire what belongs to others, but will rejoice in their prosperity, giving glory to God.”

2. Ps. lxxii. 26.

3. I Kings, xvi. 7.

4. Eccles., v. 9.

5. “Confessions,” I.

6. Ps. cii. 5.

7. Eccles., v. 11.

8. Matt. vi. 21.

9. Luke viii. 14.

10. Ecclus., xiv. 3.

11. Exod., xxiii. 8.

12. Ecclus., xxxi. 5.

13. “Ibid.,” vii. 20.

14. Matt., vi. 24.

15. I Tim., vi. 9, 10.

16. “Another reason for these two Commandments is that they clearly and in definite terms forbid some things not expressly prohibited in the Sixth and Seventh Commandments. The Seventh Commandment, for instance, forbids an unjust desire to take what belongs to another; but the Tenth Commandment further prohibits even to covet it in any way, even though it could be acquired justly and lawfully–if we foresee that by such acquisition our neighbor would suffer some loss. . . . Another reason why this sort of vicious desire is condemned is that it has for its object that which belongs to another, such as a house, maidservant, field, wife, ox, ass, and many other things, all of which the law of God forbids us to covet, simply because they belong to another. The desire for such things, when consented to, is criminal, and is numbered among the most grievous sins. When the mind, yielding to the impulse of evil desires, is pleased with evil or does not resist it, sin is necessarily committed” (“Roman Catechism,” loc. cit.,” 11).

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