(a) Its object is sexual pleasure, that is, the sense of physical enjoyment in the bodily organs or of psychical satisfaction in the lower appetites of the soul derived from acts related to generation. Hence, we should distinguish impurity from sensuality (which is an inordinate attachment to esthetic pleasure or other higher sense-pleasure), from luxury (which is an excessive desire of health and comfort), and from the vice called curiosity (which is an over-fondness for intellectual delights, see 2461). But it should be noted that sensual pleasure easily leads to venereal delight, and that intellectual curiosity about sex matters is dangerous, and hence this sensuality and curiosity may be, and frequently are, a temptation to impurity (see below on Temptations to Impurity).
(b) Impurity is in desire, for the passions in themselves are indifferent (see 121), and they become sinful only when their abuse is consented to by the will.
(c) Impurity is inordinate; that is, it takes pleasure against lhe dictate of reason. This happens when sexual gratifications are indulged by the unmarried, or by the married in unnatural ways. It is a perversion and a sin to cheat the stomach in order to gratify the palate, because God willed that the pleasure of eating should serve the nourishment of the body, or, as the proverb has it, because man does not live to eat, but eats to live. Now, sex pleasure has been ordained by God as an inducement to perform an act which has for its purpose the propagation and education of children, duties that cannot be rightly attended to except in the married state. Hence, those who seek venereal pleasure outside of matrimony, or outside the way intended by nature, act unreasonably, for they sacrifice the end for the means. Instinct guides the animal aright in these matters, but man is a nobler creature and must guide himself by religion and reason.
2493. Kinds of Impurity.—(a) Impurity is consummated when the act is continued to its natural conclusion and complete venereal satisfaction is had. This occurs in semination, which is the termination of the process set up by the impure thought and desire and the realization of its full pleasure. Semination occurs either in the process of coition, or in extracoitional issues known as “pollution.” Equivalent to semination, morally speaking, are other emissions or secretions that accompany complete or almost complete gratification, but in which the fluid is not prolific (e.g., the urethral emissions in boys who have not attained puberty or in eunuchs, the vaginal flow in women, urethral distillations). Consummated impurity is either natural (that is, suitable for reproduction, the end intended by nature), as in fornication or adultery, or unnatural (that is, not suited for reproduction), as in sodomy or pollution.
(b) Impurity is non-consummated when not carried to its natural conclusion of complete satisfaction and semination. There are two classes of the non-consummated sins, namely, the internal (as in thoughts and desires) and the external or lewdness (as in words, looks, kisses). This happens without carnal commotion (e.g., when a frigid old man thinks with mental pleasure only on the wild deeds of his youth), or with carnal commotion, that is, with an excitement and stimulation in the genital organs that prepares the way for semination.
2494. Gravity of the Sin of Impurity.—(a) Impurity is a mortal sin, because it is a disorder that affects a good of the highest importance (viz, the propagation of the race), and brings in its train public and private, moral and physical, evils of the most serious kind. Man has no more right to degrade his body by lust than he has to kill it by suicide, for God is the absolute Lord over the body and He severely forbids impurity of every kind. Those who do the works of the flesh, whether according to nature (e.g., fornicators and adulterers) or against nature (e.g., sodomites) or by unconsummated sin (e.g., the unclean, the impure), shall not obtain the kingdom of God (Gal., v. 19; I Cor., vi. 9 sqq.), nor have any inheritance with Christ (Eph., v. 5).
(b) Impurity is not the worst of sins, because sins against God (e.g., hatred of God, sacrilege) are more heinous than sins against created goods, and sins of malice are more inexcusable than sins of passion or frailty. But carnal sins are peculiarly disgraceful on account of their animality (see 2464 b, 224), and in a Christian they are a kind of profanation, since his body has been given to Christ in Baptism and the other Sacraments (I Cor., vi. 11-19).
(c) Impurity is one of the seven capital vices. The capital sins have a preeminence in evil, as the cardinal virtues have a superiority in good. The preeminence in evil is due, first, to some special attractiveness of a vice that makes it an end for the commission of other sins, which are used as means to it or are incurred for its sake; or, secondly, to a power and influence that is so strong as to hurry those under its sway into various kinds of sin. Now, impurity is a moral disease that ravages every part of the soul, its deadly effects appearing in the reason, the will and external speech; for the more one subjects oneself to the dominion of passion, the less fitted does one become for the higher and nobler things of life; and the more ignoble the inner life, the more vulgar, cheap and degrading will be the conversation.
Hence, the Fathers trace back to impurity the following sins of imprudence in the mind: wrong apprehension, about the end or purpose of life, and precipitancy in deliberation, thoughtlessness in decision, inconstancy in direction, in reference to the means to the end (see 1693 sqq.). They also trace to impurity the following sins in the will: as to the end, voluptuarism (which subordinates all to fleshly pleasure) and hatred of God (which abhors the Supreme Lawgiver who forbids and punishes lust); as to the means, love of the present and horror of the future life (since the carnal man revels in bodily pleasures and dreads the thought of death and judgment). Finally, they trace the following sins of the tongue to the vice of impurity: the subject of the lewd man’s talk is filthy, for out of the heart the mouth speaketh (Matt., xii. 34), the expression itself is foolish, since passion clouds his mind, the origin of his talk is emptiness of mind which shows itself in frivolous words, and his purpose is unsuitable amusement, which leads to farcical or vulgar jokes.
2495. Evil Fruits of Impurity.—In addition to these moral consequences, impurity is also prolific of many other evil fruits.