The Catechism of St. Thomas Aquinas


The Lord specifically forbids injury to our neighbor in the Commandments. Thus, “Thou shalt not kill” forbids us to injure our neighbor in his own person; “Thou shalt not commit adultery” forbids injury to the person to whom one is bound in marriage; and now the Commandment, “Thou shalt not steal,” forbids us to injure our neighbor in his goods. This Commandment forbids any worldly goods whatsoever to be taken away wrongfully.[1]

Theft is committed in a number of ways. First, by taking stealthily: “If the goodman of the house knew at what hour the thief would come.”[2] This is an act wholly blameworthy because it is a form of treachery. “Confusion . . . is upon the thief.”[3]

Secondly, by taking with violence, and this is an even greater injury: “They have violently robbed the fatherless.”[4] Among such that do such things are wicked kings and rulers: “Her princes are in the midst of her as roaring lions; her judges are evening wolves, they left nothing for the morning.”[5] They act contrary to God’s will who wishes a rule according to justice: “By Me kings reign and lawgivers decree just things.”[6] Sometimes they do such things stealthily and sometimes with violence: “Thy princes are faithless companions of thieves, they all love bribes, they run after rewards.”[7] At times they steal by enacting laws and enforcing them for profit only: “Woe to them that make wicked laws.”[8] And St. Augustine says that every wrongful usurpation is theft when he asks: “What are thrones but forms of thievery?”[9]

Thirdly, theft is committed by not paying wages that are due: “The wages of him that hath been hired by thee shall not abide by thee until the morning.”[10] This means that a man must pay every one his due, whether he be prince, prelate, or cleric, etc.: “Render therefore to all men their dues. Tribute, to whom tribute is due, custom, to whom custom.”[11] Hence, we are bound to give a return to rulers who guard our safety.

The fourth kind of theft is fraud in buying and selling: “Thou shalt not have divers weights in thy bag, a greater and a less.”[12] And again: “Do not any unjust thing in judgment, in rule, in weight, or in measure.”[13] All this is directed against the keepers of wine-shops who mix water with the wine. Usury is also forbidden: “Who shall dwell in Thy tabernacle, or who shall rest in Thy holy hill? . . . He that hath not put his money out to usury.”[14] This is also against money-changers who commit many frauds, and against the sellers of cloth and other goods.

Fifthly, theft is committed by those who buy promotions to positions of temporal or spiritual honor. “The riches which he hath swallowed, he shall vomit up, and God shall draw them out of his belly,”[15] has reference to temporal position. Thus, all tyrants who hold a kingdom or province or land by force are thieves, and are held to restitution. Concerning spiritual dignities: “Amen, amen, I say to you, he that entereth not by the door into the sheepfold but climbeth up another way is a thief and a robber.”[16] Therefore, they who commit simony are thieves.


“Thou shalt not steal.” This Commandment, as has been said, forbids taking things wrongfully, and we can bring forth many reasons why it is given. The first is because of the gravity of this sin, which is likened to murder: “The bread of the needy is the life of the poor; he that defraudeth them thereof is a man of blood.”[18] And again: “He that sheddeth blood and he that defraudeth the laborer of his hire are brothers.”[19]

The second reason is the peculiar danger involved in theft, for no sin is so dangerous. After committing other sins a person may quickly repent, for instance, of murder when his anger cools, or of fornication when his passion subsides, and so on for others; but even if one repents of this sin, one does not easily make the necessary satisfaction for it. This is owing to the obligation of restitution and the duty to make up for what loss is incurred by the rightful owner. And all this is above and beyond the obligation to repent for the sin itself: “Woe to him that heapeth together that which is not his own, how long doth he load himself with thick clay!”[20] For thick clay is that from which one cannot easily extricate himself.[21]

The third reason is the uselessness of stolen goods in that they are of no spiritual value: “Treasures of wickedness shall profit nothing.”[22] Wealth can indeed be useful for almsgiving and offering of sacrifices, for “the ransom of a man’s life are his riches.”[23] But it is said of stolen goods: “I am the Lord that love judgment, and hate robbery in a holocaust.”[24]. And again: “He that offereth sacrifice of the goods of the poor is as one that sacrificeth the son in the presence of his father.”[25]

The fourth reason is that the results of theft are peculiarly harmful to the thief in that they lead to his loss of other goods. It is not unlike the mixture of fire and straw: “Fire shall devour their tabernacles, who love to take bribes.”[26] And it ought to be known that a thief may lose not only his own soul, but also the souls of his children, since they are bound to make restitution.

(For “Questions for Discussion” see Chapter 6.)


1. St. Thomas also treats of this Commandment in the “Summa Theol.,” II-II, Q. cxxii, Art. 6.

2. Matt., xxiv. 43.

3. Ecclus., v. 17.

4. Job, xxiv. 9.

5. Soph., iii. 3.

6. Prov., viii. 15.

7. Isa., i. 23.

8. “Ibid.,” x. 1.

9. “The City of God,” IV, 4. “It must be seen that the word ‘steal’ is understood not only of the taking away of anything from its rightful owner privately and witbout his consent, but also the possession of that which belongs to another, contrary to his will, although not without his knowledge. Otherwise we would say that he who forbids theft does not also forbid robbery, which is accomplished by violence and injustice. . . . So robbery is a greater sin than theft, inasmuch as it not only deprives another of his property, but also offers violence and insult to him. Nor can it be a matter of surprise that the Commandment is expressed in the lighter word, ‘steal,’ instead of ‘rob.’ A good reason for this is that theft is more general and of wider extent than robbery” (“Roman Catechism,” “Seventh Commandment,” 3-4).

10. Lev., xix. 13.

11. Rom., xiii. 7.

R=#000000>12. Deut., xxv. 13.

13. Lev., xix. 35-36.

14. Ps. xiv. 1, 5.

15. Job, xx. 15.

16. John, x. 1.

18. Ecclus., xxxiv. 25.

19. “Ibid.,” 27.

20. Hab., ii. 6.

21. “The possession of other men’s property is called ‘thick clay’ by the prophet because it is difficult to emerge and disengage oneself from [illgotten goods]. . . . What shall we say of the obligation imposed by God on all of satisfying for the injury done? ‘Without restitution,’ says St. Augustine, ‘the sin is not forgiven’ ” (“Roman Catechism,” “loc. cit.,” 8).

22. Prov., x. 2.

23. “Ibid.,” xiii. 8.

24. Isa., lxi. 8.

25. Ecclus., xxxiv. 24.

26. Job, xv. 34.

If you liked this post, you should join Jimmy's Secret Information Club to get more great info!

What is the Secret Information Club?I value your email privacy