CATECHISM OF THE CATHOLIC CHURCH
SECOND EDITION

Paragraphs 2532–2536

2532 Purification of the heart demands prayer, the practice of chastity, purity of intention and of vision.
2533 Purity of heart requires the modesty which is patience, decency, and discretion. Modesty protects the intimate center of the person.

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."