Thomas Aquinas

“ The excess of passion that amounts to a sin does not refer to the passion's quantitative intensity, but to its proportion to reason; wherefore it is only when a passion goes beyond the bounds of reason that it is reckoned to be immoderate. Now the pleasure attaching to the marriage act, while it is most intense in point of quantity, does not go beyond the bounds previously appointed by reason before the commencement of the act, although reason is unable to regulate them during the pleasure itself. ”

“ If then marriage can be righted by certain goods, it needs nothing else to right it besides the virtues of the soul; and consequently there is no need to assign to matrimony any goods whereby it is righted, any more than to other things in which the virtues direct us. ”

“ It would seem that the marriage act cannot be altogether excused from sin by the aforesaid goods. For whoever allows himself to lose a greater good for the sake of a lesser good sins because he allows it inordinately. Now the good of reason which is prejudiced in the marriage act is greater than these three marriage goods. Therefore the aforesaid goods do not suffice to excuse marriage intercourse. ”

“ First, in themselves, and thus they regard the use of matrimony in begetting children and observing the marriage compact; while inseparability, which is denoted by "sacrament," regards the very sacrament considered in itself, since from the very fact that by the marriage compact man and wife give to one another power the one over the other in perpetuity, it follows that they cannot be put asunder. Hence there is no matrimony without inseparability, whereas there is matrimony without "faith" and "offspring," because the existence of a thing does not depend on its use ”

“ An act of virtue may derive its rectitude both from the virtue as its elicitive principle, and from its circumstances as its formal principles; and the goods of marriage are related to marriage as circumstances to an act of virtue which owes it to those circumstances that it can be an act of virtue. ”

“ Just as the right use of a useful good derives its rectitude not from the useful but from the reason which causes the right use, so too direction to a useful good may cause the goodness of rectitude by virtue of the reason causing the right direction; and in this way marriage, through being directed to the offspring, is useful, and nevertheless righteous, inasmuch as it is directed aright. ”

“ Although the consent which makes a marriage is not everlasting materially, i.e. in regard to the substance of the act, since that act ceases and a contrary act may succeed it, nevertheless formally speaking it is everlasting, because it is a consent to an ever lasting bond, else it would not make a marriage, for a consent to take a woman for a time makes no marriage. Hence it is everlasting formally, inasmuch as an act takes its species from its object; and thus it is that matrimony derives its inseparability from the consent. ”

“ The offspring considered as a marriage good includes something besides the offspring as a good intended by nature. For nature intends offspring as safeguarding the good of the species, whereas the offspring as a good of the sacrament of marriage includes besides this the directing of the child to God. Wherefore the intention of nature which intends the offspring must needs be referred either actually or habitually to the intention of having an offspring, as a good of the sacrament: otherwise the intention would go no further than a creature; and this is always a sin. ”

“ One due circumstance does not suffice to make a good act, and consequently it does not follow that, no matter how one use one's own property, the use is good, but when one uses it as one ought according to all the circumstances. ”

“ Further, if a moral good be added to a moral evil the sum total is evil and not good, since one evil circumstance makes an action evil, whereas one good circumstance does not make it good. Now the marriage act is evil in itself, else it would need no excuse. Therefore the addition of the marriage goods cannot make the act good. ”

“ Further, whoever fails to refer the use of a creature to God enjoys a creature, and this is a mortal sin. But whoever uses his wife for mere pleasure does not refer that use to God. Therefore he sins mortally. ”

“ Hence, in order to entice a man to take food which supplies a defect of the individual, it is enough that he feel this defect; but in order to entice him to the act whereby a defect of the species is remedied, Divine providence attached pleasure to that act, which moves even irrational animals in which there is not the stain of original sin. ”

“ Although he does not actually refer the pleasure to God, he does not place his will's last end therein; otherwise he would seek it anywhere indifferently. Hence it does not follow that he enjoys a creature; but he uses a creature actually for his own sake, and himself habitually, though not actually, for God's sake. ”

“ Hence the marriage bond does not last after the life wherein it is contracted, and consequently it is said to be inseparable, because it cannot be sundered in this life, but either by bodily death after carnal union, or by spiritual death after a merely spiritual union. ”

“ The reason for this statement is not that man deserves to be excommunicated for this sin, but because he renders himself unfit for spiritual things, since in that act, he becomes flesh and nothing more. ”