CATECHISM OF THE CATHOLIC CHURCH
SECOND EDITION

Paragraphs 2534–2537

You shall not covet . . . anything that is your neighbor's. . . . You shall not desire your neighbor's house, his field, or his manservant, or his maidservant, or his ox, or his ass, or anything that is your neighbor's.
For where your treasure is, there will your heart be also.

2534 The tenth commandment unfolds and completes the ninth, which is concerned with concupiscence of the flesh. It forbids coveting the goods of another, as the root of theft, robbery, and fraud, which the seventh commandment forbids. "Lust of the eyes" leads to the violence and injustice forbidden by the fifth commandment. Avarice, like fornication, originates in the idolatry prohibited by the first three prescriptions of the Law. The tenth commandment concerns the intentions of the heart; with the ninth, it summarizes all the precepts of the Law.

2535 The sensitive appetite leads us to desire pleasant things we do not have, e.g., the desire to eat when we are hungry or to warm ourselves when we are cold. These desires are good in themselves; but often they exceed the limits of reason and drive us to covet unjustly what is not ours and belongs to another or is owed to him.
2536 The tenth commandment forbids greed and the desire to amass earthly goods without limit. It forbids avarice arising from a passion for riches and their attendant power. It also forbids the desire to commit injustice by harming our neighbor in his temporal goods:

When the Law says, "You shall not covet," these words mean that we should banish our desires for whatever does not belong to us. Our thirst for another's goods is immense, infinite, never quenched. Thus it is written: "He who loves money never has money enough."

2537 It is not a violation of this commandment to desire to obtain things that belong to one's neighbor, provided this is done by just means. Traditional catechesis realistically mentions "those who have a harder struggle against their criminal desires" and so who "must be urged the more to keep this commandment":

. . . merchants who desire scarcity and rising prices, who cannot bear not to be the only ones buying and selling so that they themselves can sell more dearly and buy more cheaply; those who hope that their peers will be impoverished, in order to realize a profit either by selling to them or buying from them . . . physicians who wish disease to spread; lawyers who are eager for many important cases and trials.