Lust
The inordinate craving for, or indulgence of, the carnal pleasure which is experienced in the human organs of generation.
The wrongfulness of lust is reducible to this: that venereal satisfaction is sought for either outside wedlock or, at any rate, in a manner which is contrary to the laws that govern marital intercourse. Every such criminal indulgence is a mortal sin, provided of course, it be voluntary in itself and fully deliberate. This is the testimony of St. Paul in the Epistle to the Galatians, v. 19:
“Now the works of the flesh are manifest, which are fornication, uncleanness, immodesty, luxury, . . . Of the which I foretell you, as I have foretold to you, that they who do such things shall not obtain the kingdom of God.”
Moreover, if it be true the gravity of the offences may be measured by the harm they work to the individual or the community, there can be no doubt that lust has in this respect a gravity all its own. Transgressions against the virtues other than purity frequently admit of a minor degree of malice, and are accounted venial. Impurity has the evil distinction that, whenever there is a direct conscious surrender to any of its phases the guilt incurred is always grievous. This judgment, however, needs modifying when there is question of some impure gratification for which a person is responsible, not immediately, but because he had posited its cause, and to which he has not deliberately consented. The act may then be only venially sinful. For the determination of the amount of its wickedness much will depend upon the apprehended proximate danger of giving way on the part of the agent, as well as upon the known capacity of the thing done to bring about venereal pleasure. This teaching applies to external and internal sins alike: “Whosoever shall look on a woman to lust after her, hath already committed adultery with her in his heart” (Matthew 5:28). However the case may stand as to the extent of the obligation under which one lies to refrain in certain circumstances from actions whose net result is to excite the passions, moralists are at one as to the counsel they give. They all emphasize the perils of the situation, and point out the practical dangers of a failure to refrain. It matters not that there is not, as we suppose, an initial sinful intent. The sheerest prudence and most rudimentary self-knowledge alike demand abstinence, where possible, from things which, though not grievously bad in themselves, yet easily fan into flame the unholy fire which may be smouldering, but it is not extinct.
Lust is said to be a capital sin. The reason is obvious. The pleasure which this vice has as its object is at once so attractive and connatural to human nature as to whet keenly a man’s desire, and so lead him into the commission of many other disorders in the pursuit of it. Theologians ordinarily distinguish various forms of lust in so far as it is a consummated external sin, e.g., fornication, adultery, incest, criminal assault, abduction, and sodomy. Each of these has its own specific malice–a fact to borne in mind for purposes of safeguarding the integrity of sacramental confession.
newadvent.org/cathen/09438a.htm
