Youcat commented through CCC – Question n. 462.

YOUCAT Question n. 462 - Why does the Ninth Commandment forbid sexual desire?

(Youcat answer) The Ninth Commandment forbids, not desires per se, but rather disordered desires. The “covetousness” against which Sacred Scripture warns is the rule of impulses over the mind, the dominion of urges over the whole person, and the sinfulness that that causes.

A deepening through CCC

(CCC 2528) "Everyone who looks at a woman lustfully has already committed adultery with her in his heart" (Mt 5:28). (CCC 2529) The ninth commandment warns against lust or carnal concupiscence. (CCC 2514) St. John distinguishes three kinds of covetousness or concupiscence: lust of the flesh, lust of the eyes, and pride of life (Cf. 1 Jn 2:16). In the Catholic catechetical tradition, the ninth commandment forbids carnal concupiscence; the tenth forbids coveting another's goods. 

 

Reflecting and meditating 

(Youcat comment) The erotic attraction between man and woman was created by God and is therefore good; it is part of a person’s sexual nature and biological constitution. It ensures that man and woman can unite with one another and descendants can spring from their love. The Ninth Commandment is meant to protect this union. The shelter of marriage and family must not be endangered through playing with fire, in other words, through reckless indulgence in the erotic energy that crackles between man and woman. That is why it is a good rule, especially for Christians: “Keep your hands off married men and women!”

(CCC Comment)

(CCC 2515) Etymologically, "concupiscence" can refer to any intense form of human desire. Christian theology has given it a particular meaning: the movement of the sensitive appetite contrary to the operation of the human reason. The apostle St. Paul identifies it with the rebellion of the "flesh" against the "spirit" (Cf. Gal 5:16, 17, 24; Eph 2:3). Concupiscence stems from the disobedience of the first sin. It unsettles man's moral faculties and, without being in itself an offense, inclines man to commit sins (Cf. Gen 3:11; Council of Trent: DS 1515).   

(The next question is: How does one achieve “purity of heart”?)