Aquinas on Sex
Thomas Aquinas (1224/25-75) is commonly regarded as the greatest Western philosopher of the thirteenth century. In a series of works he addressed all the current issues of theology and philosophy, and in particular the problem Christian thinkers had in dealing with the arrival of good editions of the works of Aristotle in the West.
Aquinas was both intensely productive and quite flexible in his approaches. [On occasion he reportedly was able to write, via dictation, two ore more works at a time]. Because of the formidable extent of his works, it is often his two great summas to which we turn to find out what he thought. This is not always wise. The summas were consciously written as compendia, and Aquinas addressed a number of theoretical issues in smaller subject specific treatises. Moreover, many of the common questions in thirteenth centuiy academic discussion were based on questions from the basic Theologiael textbook, Peter Lombard's Four Books of Sentences, and it is to Aquinas' commentaries on these that one should turn for his discussion of issues such as women clergy, or the moment of consecration.
The summas [the Summa Theologiae and the Summa Contra Gentiles] are, however, useful. Echoing the disputation methods of university teaching, the Summa Theologiae
presents a summation of Aquinas' opinions on issues from the existence of God, to the sacremental system, to basic moral rules.
The selection here addresses Aquinas discussion of sex and sexuality. It shows both his typical methods - his willingness to face objections openly, his use of authorities, and his use of logic - as well as the effort to construct the intractable realities of human experience into a structured and analyzable form.
Extracts from Summa Theologiae II-II, questions 153 and 154
The following issues, from the sinfulness of fornication, to sexual petting, to rape and incest, are addressed by Aquinas in these selections:-
Aquinas' discussion of unnatural sex [which includes homosexuality, bestiality and masturbation], is available in a separate document, Aquinas on Unnatural Sex
- Summa Theologiae II-II, 153, 2: Whether no venereal act can be without sin?
- Summa Theologiae II-II, 153, 3: Whether the lust that is about venereal acts can be a sin?
- Summa Theologiae II-II, 154, 1: Whether six species are fittingly assigned to lust?
- Summa Theologiae II-II, 154, 2: Whether simple fornication is a mortal sin?
- Summa Theologiae II-II, 154, 3: Whether fornication is the most grievous of sins?
- Summa Theologiae II-II, 154, 4: Whether there can be mortal sin in touches and kisses?
- Summa Theologiae II-II, 154, 5: Whether nocturnal pollution is a mortal sin?
- Summa Theologiae II-II, 154, 6: Whether seduction should be reckoned a species of lust?
- Summa Theologiae II-II, 154, 7: Whether rape is a species of lust, distinct from seduction?
- Summa Theologiae II-II, 154, 8: Whether adultery is determinate species of lust, distinct from the other species?
- Summa Theologiae II-II, 154, 9: Whether incest is a determinate species of lust?
- Summa Theologiae II-II, 154, 10: Whether sacrilege can be a species of lust?
Summa Theologiae II-II, 153, 2
Whether no venereal act can be without sin?
Objection 1. It would seem that no venereal act can be without sin. For
nothing but sin would seem to hinder virtue. Now every venereal act is a
great hindrance to virtue. For Augustine says (Soliloq. i, 10): "I
consider that nothing so casts down the manly mind from its height as the
fondling of a woman, and those bodily contacts." Therefore, seemingly, no
venereal act is without sin.
Objection 2. Further, any excess that makes one forsake the good of reason is
sinful, because virtue is corrupted by "excess" and "deficiency" as
stated in Ethic. ii, 2. Now in every venereal act there is excess of
pleasure, since it so absorbs the mind, that "it is incompatible with the
act of understanding," as the Philosopher observes (Ethic. vii, 11); and
as Jerome [Origen, Hom. vi in Num.; Cf. Jerome, Ep. cxxiii ad Ageruch.]
states, rendered the hearts of the prophets, for the moment, insensible
to the spirit of prophecy. Therefore no venereal act can be without sin.
Objection 3. Further, the cause is more powerful than its effect. Now original
sin is transmitted to children by concupiscence, without which no
venereal act is possible, as Augustine declares (De Nup. et Concup. i,
24). Therefore no venereal act can be without sin.
On the contrary, Augustine says (De Bono Conjug. xxv): "This is a
sufficient answer to heretics, if only they will understand that no sin
is committed in that which is against neither nature, nor morals, nor a
commandment": and he refers to the act of sexual intercourse between the
patriarchs of old and their several wives. Therefore not every venereal
act is a sin.
I answer that, A sin, in human acts, is that which is against the order
of reason. Now the order of reason consists in its ordering everything to
its end in a fitting manner. Wherefore it is no sin if one, by the
dictate of reason, makes use of certain things in a fitting manner and
order for the end to which they are adapted, provided this end be
something truly good. Now just as the preservation of the bodily nature
of one individual is a true good, so, too, is the preservation of the
nature of the human species a very great good. And just as the use of
food is directed to the preservation of life in the individual, so is the
use of venereal acts directed to the preservation of the whole human
race. Hence Augustine says (De Bono Conjug. xvi): "What food is to a
man's well being, such is sexual intercourse to the welfare of the whole
human race." Wherefore just as the use of food can be without sin, if it
be taken in due manner and order, as required for the welfare of the
body, so also the use of venereal acts can be without sin, provided they
be performed in due manner and order, in keeping with the end of human
Reply to Objection 1. A thing may be a hindrance to virtue in two ways. First, as
regards the ordinary degree of virtue, and as to this nothing but sin is
an obstacle to virtue. Secondly, as regards the perfect degree of virtue,
and as to this virtue may be hindered by that which is not a sin, but a
lesser good. On this way sexual intercourse casts down the mind not from
virtue, but from the height, i.e. the perfection of virtue. Hence
Augustine says (De Bono Conjug. viii): "Just as that was good which
Martha did when busy about serving holy men, yet better still that which
Mary did in hearing the word of God: so, too, we praise the good of
Susanna's conjugal chastity, yet we prefer the good of the widow Anna,
and much more that of the Virgin Mary."
Reply to Objection 2. As stated above (152, 2, ad 2; I-II, 64, 2), the
mean of virtue depends not on quantity but on conformity with right
reason: and consequently the exceeding pleasure attaching to a venereal
act directed according to reason, is not opposed to the mean of virtue.
Moreover, virtue is not concerned with the amount of pleasure experienced
by the external sense, as this depends on the disposition of the body;
what matters is how much the interior appetite is affected by that
pleasure. Nor does it follow that the act in question is contrary to
virtue, from the fact that the free act of reason in considering
spiritual things is incompatible with the aforesaid pleasure. For it is
not contrary to virtue, if the act of reason be sometimes interrupted for
something that is done in accordance with reason, else it would be
against virtue for a person to set himself to sleep. That venereal
concupiscence and pleasure are not subject to the command and moderation
of reason, is due to the punishment of the first sin, inasmuch as the
reason, for rebelling against God, deserved that its body should rebel
against it, as Augustine says (De Civ. Dei xiii, 13).
Reply to Objection 3. As Augustine says (De Civ. Dei xiii, 13), "the child,
shackled with original sin, is born of fleshly concupiscence (which is
not imputed as sin to the regenerate) as of a daughter of sin." Hence it
does not follow that the act in question is a sin, but that it contains
something penal resulting from the first sin.
Summa Theologiae II-II, 153, 3
Whether the lust that is about venereal acts can be a sin?
Objection 1. It would seem that lust about venereal acts cannot be a sin. For
the venereal act consists in the emission of semen which is the surplus
from food, according to the Philosopher (De Gener. Anim. i, 18). But
there is no sin attaching to the emission of other superfluities.
Therefore neither can there be any sin in venereal acts.
Objection 2. Further, everyone can lawfully make what use he pleases of what
is his. But in the venereal act a man uses only what is his own, except
perhaps in adultery or rape. Therefore there can be no sin in venereal
acts, and consequently lust is no sin.
Objection 3. Further, every sin has an opposite vice. But, seemingly, no vice
is opposed to lust. Therefore lust is not a sin.
On the contrary, The cause is more powerful than its effect. Now wine is
forbidden on account of lust, according to the saying of the Apostle
(Eph. 5:18), "Be not drunk with wine wherein is lust [Douay: 'luxury']."
Therefore lust is forbidden.
Further, it is numbered among the works of the flesh: Gal. 5:19 [Douay:
I answer that, The more necessary a thing is, the more it behooves one
to observe the order of reason in its regard; wherefore the more sinful
it becomes if the order of reason be forsaken. Now the use of venereal
acts, as stated in the foregoing Article, is most necessary for the
common good, namely the preservation of the human race. Wherefore there
is the greatest necessity for observing the order of reason in this
matter: so that if anything be done in this connection against the
dictate of reason's ordering, it will be a sin. Now lust consists
essentially in exceeding the order and mode of reason in the matter of
venereal acts. Wherefore without any doubt lust is a sin.
Reply to Objection 1. As the Philosopher says in the same book (De Gener. Anim.
i, 18), "the semen is a surplus that is needed." For it is said to be
superfluous, because it is the residue from the action of the nutritive
power, yet it is needed for the work of the generative power. But the
other superfluities of the human body are such as not to be needed, so
that it matters not how they are emitted, provided one observe the
decencies of social life. It is different with the emission of semen,
which should be accomplished in a manner befitting the end for which it
Reply to Objection 2. As the Apostle says (1 Cor. 6:20) in speaking against lust,
"You are bought with a great price: glorify and bear God in your body."
Wherefore by inordinately using the body through lust a man wrongs God
Who is the Supreme Lord of our body. Hence Augustine says (De Decem.
Chord. 10 [Serm. ix (xcvi de Temp.)]): "God Who thus governs His
servants for their good, not for His, made this order and commandment,
lest unlawful pleasures should destroy His temple which thou hast begun
Reply to Objection 3. The opposite of lust is not found in many, since men are
more inclined to pleasure. Yet the contrary vice is comprised under
insensibility, and occurs in one who has such a dislike for sexual
intercourse as not to pay the marriage debt.
Summa Theologiae II-II, 154, 1
Whether six species are fittingly assigned to lust?
Objection 1. It would seem that six species are unfittingly assigned to lust,
namely, "simple fornication, adultery, incest, seduction, rape, and the
unnatural vice." For diversity of matter does not diversify the species.
Now the aforesaid division is made with regard to diversity of matter,
according as the woman with whom a man has intercourse is married or a
virgin, or of some other condition. Therefore it seems that the species
of lust are diversified in this way.
Objection 2. Further, seemingly the species of one vice are not differentiated
by things that belong to another vice. Now adultery does not differ from
simple fornication, save in the point of a man having intercourse with
one who is another's, so that he commits an injustice. Therefore it seems
that adultery should not be reckoned a species of lust.
Objection 3. Further, just as a man may happen to have intercourse with a
woman who is bound to another man by marriage, so may it happen that a
man has intercourse with a woman who is bound to God by vow. Therefore
sacrilege should be reckoned a species of lust, even as adultery is.
Objection 4. Further, a married man sins not only if he be with another woman,
but also if he use his own wife inordinately. But the latter sin is
comprised under lust. Therefore it should be reckoned among the species
Objection 5. Further, the Apostle says (2 Cor. 12:21): "Lest again, when I
come, God humble me among you, and I mourn many of them /that sinned
before, and have not done penance for the uncleanness and fornication and
lasciviousness that they have committed." Therefore it seems that also
uncleanness and lasciviousness should be reckoned species of lust, as
well as fornication.
Objection 6. Further, the thing divided is not to be reckoned among its parts.
But lust is reckoned together with the aforesaid: for it is written (Gal.
5:19): "The works of the flesh are manifest, which are fornication,
uncleanness, immodesty, lust [Douay: 'luxury']." Therefore it seems that
fornication is unfittingly reckoned a species of lust.
On the contrary, The aforesaid division is given in the Decretals 36,
qu. i [Append. Grat. ad can. Lex illa].
I answer that As stated above (153, 3), the sin of lust consists
in seeking venereal pleasure not in accordance with right reason. This
may happen in two ways. First, in respect of the matter wherein this
pleasure is sought; secondly, when, whereas there is due matter, other
due circumstances are not observed. And since a circumstance, as such,
does not specify a moral act, whose species is derived from its object
which is also its matter, it follows that the species of lust must be
assigned with respect to its matter or object.
Now this same matter may be discordant with right reason in two ways.
First, because it is inconsistent with the end of the venereal act. On
this way, as hindering the begetting of children, there is the "vice
against nature," which attaches to every venereal act from which
generation cannot follow; and, as hindering the due upbringing and
advancement of the child when born, there is "simple fornication," which
is the union of an unmarried man with an unmarried woman. Secondly, the
matter wherein the venereal act is consummated may be discordant with
right reason in relation to other persons; and this in two ways. First,
with regard to the woman, with whom a man has connection, by reason of
due honor not being paid to her; and thus there is "incest," which
consists in the misuse of a woman who is related by consanguinity or
affinity. Secondly, with regard to the person under whose authority the
woman is placed: and if she be under the authority of a husband, it is
"adultery," if under the authority of her father, it is "seduction," in
the absence of violence, and "rape" if violence be employed.
These species are differentiated on the part of the woman rather than of
the man, because in the venereal act the woman is passive and is by way
of matter, whereas the man is by way of agent; and it has been stated
above (Objection 1) that the aforesaid species are assigned with regard to a
difference of matter.
Reply to Objection 1. The aforesaid diversity of matter is connected with a
formal difference of object, which difference results from different
modes of opposition to right reason, as stated above.
Reply to Objection 2. As stated above (I-II, 18, 07), nothing hinders the
deformities of different vices concurring in the one act, and in this way
adultery is comprised under lust and injustice. Nor is this deformity of
injustice altogether accidental to lust: since the lust that obeys
concupiscence so far as to lead to injustice, is thereby shown to be more
Reply to Objection 3. Since a woman, by vowing continence, contracts a spiritual
marriage with God, the sacrilege that is committed in the violation of
such a woman is a spiritual adultery. On like manner, the other kinds of
sacrilege pertaining to lustful matter are reduced to other species of
Reply to Objection 4. The sin of a husband with his wife is not connected with
undue matter, but with other circumstances, which do not constitute the
species of a moral act, as stated above (I-II, 18, 2).
Reply to Objection 5. As a gloss says on this passage, "uncleanness" stands for
lust against nature, while "lasciviousness" is a man's abuse of boys,
wherefore it would appear to pertain to seduction. We may also reply that
"lasciviousness" relates to certain acts circumstantial to the venereal
act, for instance kisses, touches, and so forth.
Reply to Objection 6. According to a gloss on this passage "lust" there signifies
any kind of excess.
Summa Theologiae II-II, 154, 2
Whether simple fornication is a mortal sin?
Objection 1. It would seem that simple fornication is not a mortal sin. For
things that come under the same head would seem to be on a par with one
another. Now fornication comes under the same head as things that are not
mortal sins: for it is written (Acts 15:29): "That you abstain from
things sacrificed to idols, and from blood, and from things strangled,
and from fornication." But there is not mortal sin in these observances,
according to 1 Tim. 4:4, "Nothing is rejected that is received with
thanksgiving." Therefore fornication is not a mortal sin.
Objection 2. Further, no mortal sin is the matter of a Divine precept. But the
Lord commanded (Osee 1:2): "Go take thee a wife of fornications, and have
of her children of fornications." Therefore fornication is not a mortal
Objection 3. Further, no mortal sin is mentioned in Holy Writ without
disapprobation. Yet simple fornication is mentioned without
disapprobation by Holy Writ in connection with the patriarchs. Thus we
read (Gn. 16:4) that Abraham went in to his handmaid Agar; and further
on (Gn. 30:5,9) that Jacob went in to Bala and Zelpha the handmaids of
his wives; and again (Gn. 38:18) that Juda was with Thamar whom he
thought to be a harlot. Therefore simple fornication is not a mortal sin.
Objection 4. Further, every mortal sin is contrary to charity. But simple
fornication is not contrary to charity, neither as regards the love of
God, since it is not a sin directly against. God, nor as regards the love
of our neighbor, since thereby no one is injured. Therefore simple
fornication is not a mortal sin.
Objection 5. Further, every mortal sin leads to eternal perdition. But simple
fornication has not this result: because a gloss of Ambrose [The
quotation is from the Gloss of Peter Lombard, who refers it to St.
Ambrose: whereas it is from Hilary the deacon] on 1 Tim. 4:8, "Godliness
is profitable to all things," says: "The whole of Christian teaching is
summed up in mercy and godliness: if a man conforms to this, even though
he gives way to the inconstancy of the flesh, doubtless he will be
punished, but he will not perish." Therefore simple fornication is not a
Objection 6. Further, Augustine says (De Bono Conjug. xvi) that "what food is
to the well-being of the body, such is sexual intercourse to the welfare
of the human race." But inordinate use of food is not always a mortal
sin. Therefore neither is all inordinate sexual intercourse; and this
would seem to apply especially to simple fornication, which is the least
grievous of the aforesaid species.
On the contrary, It is written (Tob. 4:13): "Take heed to keep thyself .
. . from all fornication, and beside thy wife never endure to know a
crime." Now crime denotes a mortal sin. Therefore fornication and all
intercourse with other than one's wife is a mortal sin.
Further, nothing but mortal sin debars a man from God's kingdom. But
fornication debars him, as shown by the words of the Apostle (Gal. 5:21),
who after mentioning fornication and certain other vices, adds: "They who
do such things shall not obtain the kingdom of God." Therefore simple
fornication is a mortal sin.
Further, it is written in the Decretals (XXII, qu. i, can.
Praedicandum): "They should know that the same penance is to be enjoined
for perjury as for adultery, fornication, and wilful murder and other
criminal offenses." Therefore simple fornication is a criminal or mortal
I answer that, Without any doubt we must hold simple fornication to be a
mortal sin, notwithstanding that a gloss [St. Augustine, QQ. in Deut.,
qu. 37 on Dt. 23:17, says: "This is a prohibition against going with
whores, whose vileness is venial." For instead of "venial" it should be
"venal," since such is the wanton's trade. On order to make this evident,
we must take note that every sin committed directly against human life is
a mortal sin. Now simple fornication implies an inordinateness that
tends to injure the life of the offspring to be born of this union. For
we find in all animals where the upbringing of the offspring needs care
of both male and female, that these come together not indeterminately,
but the male with a certain female, whether one or several; such is the
case with all birds: while, on the other hand, among those animals, where
the female alone suffices for the offspring's upbringing, the union is
indeterminate, as in the case of dogs and like animals. Now it is evident
that the upbringing of a human child requires not only the mother's care
for his nourishment, but much more the care of his father as guide and
guardian, and under whom he progresses in goods both internal and
external. Hence human nature rebels against an indeterminate union of the
sexes and demands that a man should be united to a determinate woman and
should abide with her a long time or even for a whole lifetime. Hence it
is that in the human race the male has a natural solicitude for the
certainty of offspring, because on him devolves the upbringing of the
child: and this certainly would cease if the union of sexes were
This union with a certain definite woman is called matrimony; which for
the above reason is said to belong to the natural law. Since, however,
the union of the sexes is directed to the common good of the whole human
race, and common goods depend on the law for their determination, as
stated above (I-II, 90, 2), it follows that this union of man and
woman, which is called matrimony, is determined by some law. What this
determination is for us will be stated in the Third Part of this work
(Supplement,050, seqq.), where we shall treat of the sacrament of matrimony.
Wherefore, since fornication is an indeterminate union of the sexes, as
something incompatible with matrimony, it is opposed to the good of the
child's upbringing, and consequently it is a mortal sin.
Nor does it matter if a man having knowledge of a woman by fornication,
make sufficient provision for the upbringing of the child: because a
matter that comes under the determination of the law is judged according
to what happens in general, and not according to what may happen in a
Reply to Objection 1. Fornication is reckoned in conjunction with these things,
not as being on a par with them in sinfulness, but because the matters
mentioned there were equally liable to cause dispute between Jews and
Gentiles, and thus prevent them from agreeing unanimously. For among the
Gentiles, fornication was not deemed unlawful, on account of the
corruption of natural reason: whereas the Jews, taught by the Divine law,
considered it to be unlawful. The other things mentioned were loathsome
to the Jews through custom introduced by the law into their daily life.
Hence the Apostles forbade these things to the Gentiles, not as though
they were unlawful in themselves, but because they were loathsome to the
Jews, as stated above (I-II, 103, 4, ad 3).
Reply to Objection 2. Fornication is said to be a sin, because it is contrary to
right reason. Now man's reason is right, in so far as it is ruled by the
Divine Will, the first and supreme rule. Wherefore that which a man does
by God's will and in obedience to His command, is not contrary to right
reason, though it may seem contrary to the general order of reason: even
so, that which is done miraculously by the Divine power is not contrary
to nature, though it be contrary to the usual course of nature. Therefore
just as Abraham did not sin in being willing to slay his innocent son,
because he obeyed God, although considered in itself it was contrary to
right human reason in general, so, too, Osee sinned not in committing
fornication by God's command. Nor should such a copulation be strictly
called fornication, though it be so called in reference to the general
course of things. Hence Augustine says (Confess. iii, 8): "When God
commands a thing to be done against the customs or agreement of any
people, though it were never done by them heretofore, it is to be done";
and afterwards he adds: "For as among the powers of human society, the
greater authority is obeyed in preference to the lesser, so must God in
preference to all."
Reply to Objection 3. Abraham and Jacob went in to their handmaidens with no
purpose of fornication, as we shall show further on when we treat of
matrimony (Supplement,065, 5, ad 2). As to Juda there is no need to excuse
him, for he also caused Joseph to be sold.
Reply to Objection 4. Simple fornication is contrary to the love of our neighbor,
because it is opposed to the good of the child to be born, as we have
shown, since it is an act of generation accomplished in a manner
disadvantageous to the future child.
Reply to Objection 5. A person, who, while given to works of piety, yields to the
inconstancy of the flesh, is freed from eternal loss, in so far as these
works dispose him to receive the grace to repent, and because by such
works he makes satisfaction for his past inconstancy; but not so as to be
freed by pious works, if he persist in carnal inconstancy impenitent
Reply to Objection 6. One copulation may result in the begetting of a man,
wherefore inordinate copulation, which hinders the good of the future
child, is a mortal sin as to the very genus of the act, and not only as
to the inordinateness of concupiscence. On the other hand, one meal does
not hinder the good of a man's whole life, wherefore the act of gluttony
is not a mortal sin by reason of its genus. It would, however, be a
mortal sin, if a man were knowingly to partake of a food which would
alter the whole condition of his life, as was the case with Adam.
Nor is it true that fornication is the least of the sins comprised under
lust, for the marriage act that is done out of sensuous pleasure is a
Summa Theologiae II-II, 154, 3
Whether fornication is the most grievous of sins?
Objection 1. It would seem that fornication is the most grievous of sins. For
seemingly a sin is the more grievous according as it proceeds from a
greater sensuous pleasure. Now the greatest sensuous pleasure is in
fornication, for a gloss on 1 Cor. 7:9 says that the "flame of sensuous
pleasure is most fierce in lust." Therefore it seems that fornication is
the gravest of sins.
Objection 2. Further, a sin is the more grievous that is committed against a
person more closely united to the sinner: thus he sins more grievously
who strikes his father than one who strikes a stranger. Now according to
1 Cor. 6:18, "He that committeth fornication sinneth against his own
body," which is most intimately connected with a man. Therefore it seems
that fornication is the most grievous of sins.
Objection 3. Further, the greater a good is, the graver would seem to be the
sin committed against it. Now the sin of fornication is seemingly opposed
to the good of the whole human race, as appears from what was said in the
foregoing Article. It is also against Christ, according to 1 Cor. 6:15,
"Shall I . . . take the members of Christ, and make them the members of a
harlot?" Therefore fornication is the most grievous of sins.
On the contrary, Gregory says (Moral. xxxiii, 12) that the sins of the
flesh are less grievous than spiritual sins.
I answer that, The gravity of a sin may be measured in two ways, first
with regard to the sin in itself, secondly with regard to some accident.
The gravity of a sin is measured with regard to the sin itself, by reason
of its species, which is determined according to the good to which that
sin is opposed. Now fornication is contrary to the good of the child to
be born. Wherefore it is a graver sin, as to its species, than those sins
which are contrary to external goods, such as theft and the like; while
it is less grievous than those which are directly against God, and sins
that are injurious to the life of one already born, such as murder.
Reply to Objection 1. The sensual pleasure that aggravates a sin is that which is
in the inclination of the will. But the sensual pleasure that is in the
sensitive appetite, lessens sin, because a sin is the less grievous
according as it is committed under the impulse of a greater passion. It
is in this way that the greatest sensual pleasure is in fornication.
Hence Augustine says (De Agone Christiano [Serm. ccxciii; ccl de Temp.;
see Appendix to St. Augustine's works]) that of all a Christian's
conflicts, the most difficult combats are those of chastity; wherein the
fight is a daily one, but victory rare: and Isidore declares (De Summo
Bono ii, 39) that "mankind is subjected to the devil by carnal lust more
than by anything else," because, to wit, the vehemence of this passion is
more difficult to overcome.
Reply to Objection 2. The fornicator is said to sin against his own body, not
merely because the pleasure of fornication is consummated in the flesh,
which is also the case in gluttony, but also because he acts against the
good of his own body by an undue resolution and defilement thereof, and
an undue association with another. Nor does it follow from this that
fornication is the most grievous sin, because in man reason is of greater
value than the body, wherefore if there be a sin more opposed to reason,
it will be more grievous.
Reply to Objection 3. The sin of fornication is contrary to the good of the human
race, in so far as it is prejudicial to the individual begetting of the
one man that may be born. Now one who is already an actual member of the
human species attains to the perfection of the species more than one who
is a man potentially, and from this point of view murder is a more
grievous sin than fornication and every kind of lust, through being more
opposed to the good of the human species. Again, a Divine good is greater
than the good of the human race: and therefore those sins also that are
against God are more grievous. Moreover, fornication is a sin against
God, not directly as though the fornicator intended to offend God, but
consequently, in the same way as all mortal sins. And just as the members
of our body are Christ's members, so too, our spirit is one with Christ,
according to 1 Cor. 6:17, "He who is joined to the Lord is one spirit."
Wherefore also spiritual sins are more against Christ than fornication is.
Summa Theologiae II-II, 154, 4
Whether there can be mortal sin in touches and kisses?
Objection 1. It would seem that there is no mortal sin in touches and kisses.
For the Apostle says (Eph. 5:3): "Fornication and all uncleanness, or
covetousness, let it not so much as be named among you, as becometh
saints," then he adds: "Or obscenity" (which a gloss refers to "kissing
and fondling"), "or foolish talking" (as "soft speeches"), "or
scurrility" (which "fools call geniality---i.e. jocularity"), and
afterwards he continues (Eph. 5:5): "For know ye this and understand that
no fornicator, or unclean, or covetous person (which is the serving of
idols), hath inheritance in the kingdom of Christ and of God," thus
making no further mention of obscenity, as neither of foolish talking or
scurrility. Therefore these are not mortal sins.
Objection 2. Further, fornication is stated to be a mortal sin as being
prejudicial to the good of the future child's begetting and upbringing.
But these are not affected by kisses and touches or blandishments.
Therefore there is no mortal sin in these.
Objection 3. Further, things that are mortal sins in themselves can never be
good actions. Yet kisses, touches, and the like can be done sometimes
without sin. Therefore they are not mortal sins in themselves.
On the contrary, A lustful look is less than a touch, a caress or a
kiss. But according to Mt. 5:28, "Whosoever shall look on a woman to lust
after her hath already committed adultery with her in his heart." Much
more therefore are lustful kisses and other like things mortal sins.
Further, Cyprian says (Ad Pompon, de Virgin., Ep. lxii), "By their very
intercourse, their blandishments, their converse, their embraces, those
who are associated in a sleep that knows neither honor nor shame,
acknowledge their disgrace and crime." Therefore by doing these things a
man is guilty of a crime, that is, of mortal sin.
I answer that, A thing is said to be a mortal works. /sin in two ways.
First, by reason of its species, and in this way a kiss, caress, or touch
does not, of its very nature, imply a mortal sin, for it is possible to
do such things without lustful pleasure, either as being the custom of
one's country, or on account of some obligation or reasonable cause.
Secondly, a thing is said to be a mortal sin by reason of its cause: thus
he who gives an alms, in order to lead someone into heresy, sins mortally
on account of his corrupt intention. Now it has been stated above (I-II,
74, 8), that it is a mortal sin not only to consent to the act, but
also to the delectation of a mortal sin. Wherefore since fornication is a
mortal sin, and much more so the other kinds of lust, it follows that in
such like sins not only consent to the act but also consent to the
pleasure is a mortal sin. Consequently, when these kisses and caresses
are done for this delectation, it follows that they are mortal sins, and
only in this way are they said to be lustful. Therefore in so far as they
are lustful, they are mortal sins.
Reply to Objection 1. The Apostle makes no further mention of these three because
they are not sinful except as directed to those that he had mentioned
Reply to Objection 2. Although kisses and touches do not by their very nature
hinder the good of the human offspring, they proceed from lust, which is
the source of this hindrance: and on this account they are mortally
Reply to Objection 3. This argument proves that such things are not mortal sins
in their species.
Summa Theologiae II-II, 154, 5
Whether nocturnal pollution is a mortal sin?
Objection 1. It would seem that nocturnal pollution is a sin. For the same
things are the matter of merit and demerit. Now a man may merit while he
sleeps, as was the case with Solomon, who while asleep obtained the gift
of wisdom from the Lord (3 Kgs. 3:2, Par. 1). Therefore a man may demerit
while asleep; and thus nocturnal pollution would seem to be a sin.
Objection 2. Further, whoever has the use of reason can sin. Now a man has the
use of reason while asleep, since in our sleep we frequently discuss
matters, choose this rather than that, consenting to one thing, or
dissenting to another. Therefore one may sin while asleep, so that
nocturnal pollution is not prevented by sleep from being a sin, seeing
that it is a sin according to its genus.
Objection 3. Further, it is useless to reprove and instruct one who cannot act
according to or against reason. Now man, while asleep, is instructed and
reproved by God, according to Job 33:15,16, "By a dream in a vision by
night, when deep sleep is wont to lay hold of men [Vulg.: 'When deep
sleep falleth upon men.' St. Thomas is apparently quoting from memory, as
the passage is given correctly above,095, 6, Objection 1 . . . Then He
openeth the ears of men, and teaching instructeth them in what they are
to learn." Therefore a man, while asleep, can act according to or against
his reason, and this is to do good or sinful actions, and thus it seems
that nocturnal pollution is a sin.
On the contrary, Augustine says (Gen. ad lit. xii, 15): "When the same
image that comes into the mind of a speaker presents itself to the mind
of the sleeper, so that the latter is unable to distinguish the imaginary
from the real union of bodies, the flesh is at once moved, with the
result that usually follows such motions; and yet there is as little sin
in this as there is in speaking and therefore thinking about such things
while one is awake."
I answer that, Nocturnal pollution may be considered in two ways. First,
in itself; and thus it has not the character of a sin. For every sin
depends on the judgment of reason, since even the first movement of the
sensuality has nothing sinful in it, except in so far as it can be
suppressed by reason; wherefore in the absence of reason's judgment,
there is no sin in it. Now during sleep reason has not a free judgment.
For there is no one who while sleeping does not regard some of the images
formed by his imagination as though they were real, as stated above in
I, 84, 8, ad 2. Wherefore what a man does while he sleeps and
is deprived of reason's judgment, is not imputed to him as a sin, as
neither are the actions of a maniac or an imbecile.
Secondly, nocturnal pollution may be considered with reference to its
cause. This may be threefold. One is a bodily cause. For when there is
excess of seminal humor in the body, or when the humor is disintegrated
either through overheating of the body or some other disturbance, the
sleeper dreams things that are connected with the discharge of this
excessive or disintegrated humor: the same thing happens when nature is
cumbered with other superfluities, so that phantasms relating to the
discharge of those superfluities are formed in the imagination.
Accordingly if this excess of humor be due to a sinful cause (for
instance excessive eating or drinking), nocturnal pollution has the
character of sin from its cause: whereas if the excess or disintegration
of these superfluities be not due to a sinful cause, nocturnal pollution
is not sinful, neither in itself nor in its cause.
A second cause of nocturnal pollution is on the part of the soul and the
inner man: for instance when it happens to the sleeper on account of some
previous thought. For the thought which preceded while he was awake, is
sometimes purely speculative, for instance when one thinks about the
sins of the flesh for the purpose of discussion; while sometimes it is
accompanied by a certain emotion either of concupiscence or of
abhorrence. Now nocturnal pollution is more apt to arise from thinking
about carnal sins with concupiscence for such pleasures, because this
leaves its trace and inclination in the soul, so that the sleeper is more
easily led in his imagination to consent to acts productive of pollution.
In this sense the Philosopher says (Ethic. i, 13) that "in so far as
certain movements in some degree pass" from the waking state to the state
of sleep, "the dreams of good men are better than those of any other
people": and Augustine says (Gen. ad lit. xii, 15) that "even during
sleep, the soul may have conspicuous merit on account of its good
disposition." Thus it is evident that nocturnal pollution may be sinful
on the part of its cause. on the other hand, it may happen that nocturnal
pollution ensues after thoughts about carnal acts, though they were
speculative, or accompanied by abhorrence, and then it is not sinful,
neither in itself nor in its cause.
The third cause is spiritual and external; for instance when by the work
of a devil the sleeper's phantasms are disturbed so as to induce the
aforesaid result. Sometimes this is associated with a previous sin,
namely the neglect to guard against the wiles of the devil. Hence the
words of the hymn at even: "Our enemy repress, that so our bodies no
uncleanness know" [Translation W. K. Blount].
On the other hand, this may occur without any fault on man's part, and
through the wickedness of the devil alone. Thus we read in the
Collationes Patrum (Coll. xxii, 6) of a man who was ever wont to suffer
from nocturnal pollution on festivals, and that the devil brought this
about in order to prevent him from receiving Holy Communion. Hence it is
manifest that nocturnal pollution is never a sin, but is sometimes the
result of a previous sin.
Reply to Objection 1. Solomon did not merit to receive wisdom from God while he
was asleep. He received it in token of his previous desire. It is for
this reason that his petition is stated to have been pleasing to God (3
Kgs. 3:10), as Augustine observes (Gen. ad lit. xii, 15).
Reply to Objection 2. The use of reason is more or less hindered in sleep,
according as the inner sensitive powers are more or less overcome by
sleep, on account of the violence or attenuation of the evaporations.
Nevertheless it is always hindered somewhat, so as to be unable to elicit
a judgment altogether free, as stated in I, 84, 8, ad 2.
Therefore what it does then is not imputed to it as a sin.
Reply to Objection 3. Reason's apprehension is not hindered during sleep to the
same extent as its judgment, for this is accomplished by reason turning
to sensible objects, which are the first principles of human thought.
Hence nothing hinders man's reason during sleep from apprehending anew
something arising out of the traces left by his previous thoughts and
phantasms presented to him, or again through Divine revelation, or the
interference of a good or bad angel.
Summa Theologiae II-II, 154, 6
Whether seduction should be reckoned a species of lust?
Objection 1. It would seem that seduction should not be reckoned a species of
lust. For seduction denotes the unlawful violation of a virgin, according
to the Decretals (XXXVI, qu. 1) [Append. Grat. ad can. Lex illa]. But
this may occur between an unmarried man and an unmarried woman, which
pertains to fornication. Therefore seduction should not be reckoned a
species of lust, distinct from fornication.
Objection 2. Further, Ambrose says (De Patriarch. [De Abraham i, 4): "Let no
man be deluded by human laws: all seduction is adultery." Now a species
is not contained under another that is differentiated in opposition to
it. Therefore since adultery is a species of lust, it seems that
seduction should not be reckoned a species of lust.
Objection 3. Further, to do a person an injury would seem to pertain to
injustice rather than to lust. Now the seducer does an injury to another,
namely the violated maiden's father, who "can take the injury as personal
to himself" [Gratian, ad can. Lex illa], and sue the seducer for
damages. Therefore seduction should not be reckoned a species of lust.
On the contrary, Seduction consists properly in the venereal act whereby
a virgin is violated. Therefore, since lust is properly about venereal
actions, it would seem that seduction is a species of lust.
I answer that, When the matter of a vice has a special deformity, we
must reckon it to be a determinate species of that vice. Now lust is a
sin concerned with venereal matter, as stated above (153, 1). And a
special deformity attaches to the violation of a virgin who is under her
father's care: both on the part of the maid, who through being violated
without any previous compact of marriage is both hindered from
contracting a lawful marriage and is put on the road to a wanton life
from which she was withheld lest she should lose the seal of virginity:
and on the part of the father, who is her guardian, according to Sirach
42:11, "Keep a sure watch over a shameless daughter, lest at any time she
make thee become a laughing-stock to thy enemies." Therefore it is
evident that seduction which denotes the unlawful violation of a virgin,
while still under the guardianship of her parents, is a determinate
species of lust.
Reply to Objection 1. Although a virgin is free from the bond of marriage, she is
not free from her father's power. Moreover, the seal of virginity is a
special obstacle to the intercourse of fornication, in that it should be
removed by marriage only. Hence seduction is not simple fornication,
since the latter is intercourse with harlots, women, namely, who are no
longer virgins, as a gloss observes on 2 Cor. 12:, "And have not done
penance for the uncleanness and fornication," etc.
Reply to Objection 2. Ambrose here takes seduction in another sense, as
applicable in a general way to any sin of lust. Wherefore seduction, in
the words quoted, signifies the intercourse between a married man and any
woman other than his wife. This is clear from his adding: "Nor is it
lawful for the husband to do what the wife may not." On this sense, too,
we are to understand the words of Num. 5:13: "If [Vulg.: 'But'] the
adultery is secret, and cannot be provided by witnesses, because she was
not found in adultery [stupro]."
Reply to Objection 3. Nothing prevents a sin from having a greater deformity
through being united to another sin. Now the sin of lust obtains a
greater deformity from the sin of injustice, because the concupiscence
would seem to be more inordinate, seeing that it refrains not from the
pleasurable object so that it may avoid an injustice. On fact a twofold
injustice attaches to it. One is on the part of the virgin, who, though
not violated by force, is nevertheless seduced, and thus the seducer is
bound to compensation. Hence it is written (Ex. 22:16,17): "If a man
seduce a virgin not yet espoused, and lie with her, he shall endow her
and have her to wife. If the maid's father will not give her to him, he
shall give money according to the dowry, which virgins are wont to
receive." The other injury is done to the maid's father: wherefore the
seducer is bound by the Law to a penalty in his regard. For it is written
(Dt. 22:28,29): "If a man find a damsel that is a virgin, who is not
espoused, and taking her, lie with her, and the matter come to judgment:
he that lay with her shall give to the father of the maid fifty sicles of
silver, and shall have her to wife, and because he hath humbled her, he
may not put her away all the days of his life": and this, lest he should
prove to have married her in mockery, as Augustine observes. [QQ. in
Dt., qu. xxxiv.]
Summa Theologiae II-II, 154, 7
Whether rape is a species of lust, distinct from seduction?
Objection 1. It would seem that rape is not a species of lust, distinct from
seduction. For Isidore says (Etym. v, 26) that "seduction [stuprum], or
rape, properly speaking, is unlawful intercourse, and takes its name from
its causing corruption: wherefore he that is guilty of rape is a
seducer." Therefore it seems that rape should not be reckoned a species
of lust distinct from seduction.
Objection 2. Further, rape, apparently, implies violence. For it is stated in
the Decretals (XXXVI, qu. 1 [Append. Grat. ad can. Lex illa]) that "rape
is committed when a maid is taken away by force from her father's house
that after being violated she may be taken to wife." But the employment
of force is accidental to lust, for this essentially regards the
pleasure of intercourse. Therefore it seems that rape should not be
reckoned a determinate species of lust.
Objection 3. Further, the sin of lust is curbed by marriage: for it is written
(1 Cor. 7:2): "For fear of fornication, let every man have his own wife."
Now rape is an obstacle to subsequent marriage, for it was enacted in the
council of Meaux: "We decree that those who are guilty of rape, or of
abducting or seducing women, should not have those women in marriage,
although they should have subsequently married them with the consent of
their parents." Therefore rape is not a determinate species of lust
distinct from seduction.
Objection 4. Further, a man may have knowledge of his newly married wife
without committing a sin of lust. Yet he may commit rape if he take her
away by force from her parents' house, and have carnal knowledge of her.
Therefore rape should not be reckoned a determinate species of lust.
On the contrary, Rape is unlawful sexual intercourse, as Isidore states
(Etym. v, 26). But this pertains to the sin of lust. Therefore rape is a
species of lust.
I answer that, Rape, in the sense in which we speak of it now, is a
species of lust: and sometimes it coincides with seduction; sometimes
there is rape without seduction, and sometimes seduction without rape.
They coincide when a man employs force in order unlawfully to violate a
virgin. This force is employed sometimes both towards the virgin and
towards her father; and sometimes towards the father and not to the
virgin, for instance if she allows herself to be taken away by force from
her father's house. Again, the force employed in rape differs in another
way, because sometimes a maid is taken away by force from her parents'
house, and is forcibly violated: while sometimes, though taken away by
force, she is not forcibly violated, but of her own consent, whether by
act of fornication or by the act of marriage: for the conditions of rape
remain no matter how force is employed. There is rape without seduction
if a man abduct a widow or one who is not a virgin. Hence Pope Symmachus
says [Ep. v ad Caesarium; Cf. can. Raptores xxxvi, qu. 2, "We abhor
abductors whether of widows or of virgins on account of the heinousness
of their crime."
There is seduction without rape when a man, without employing force,
violates a virgin unlawfully.
Reply to Objection 1. Since rape frequently coincides with seduction, the one is
sometimes used to signify the other.
Reply to Objection 2. The employment of force would seem to arise from the
greatness of concupiscence, the result being that a man does not fear to
endanger himself by offering violence.
Reply to Objection 3. The rape of a maiden who is promised in marriage is to be
judged differently from that of one who is not so promised. For one who
is promised in marriage must be restored to her betrothed, who has a
right to her in virtue of their betrothal: whereas one that is not
promised to another must first of all be restored to her father's care,
and then the abductor may lawfully marry her with her parents' consent.
Otherwise the marriage is unlawful, since whosoever steals a thing he is
bound to restore it. Nevertheless rape does not dissolve a marriage
already contracted, although it is an impediment to its being contracted.
As to the decree of the council in question, it was made in abhorrence of
this crime, and has been abrogated. Wherefore Jerome [The quotation is
from Can. Tria. xxxvi, qu. 2 declares the contrary: "Three kinds of
lawful marriage," says he, "are mentioned in Holy Writ. The first is that
of a chaste maiden given away lawfully in her maidenhood to a man. The
second is when a man finds a maiden in the city, and by force has carnal
knowledge of her. If the father be willing, the man shall endow her
according to the father's estimate, and shall pay the price of her purity
[Cf. Dt. 22:23-29. The third is, when the maiden is taken away from
such a man, and is given to another at the father's will."
We may also take this decree to refer to those who are promised to
others in marriage, especially if the betrothal be expressed by words in
the present tense.
Reply to Objection 4. The man who is just married has, in virtue of the
betrothal, a certain right in her: wherefore, although he sins by using
violence, he is not guilty of the crime of rape. Hence Pope Gelasius says
[Can. Lex illa, xxvii, qu. 2; xxxvi, qu. 1: "This law of bygone rulers
stated that rape was committed when a maiden, with regard to whose
marriage nothing had so far been decided, was taken away by force."
Summa Theologiae II-II, 154, 8
Whether adultery is determinate species of lust, distinct from the other
Objection 1. It would seem that adultery is not a determinate species of lust,
distinct from the other species. For adultery takes its name from a man
having intercourse "with a woman who is not his own [ad alteram],"
according to a gloss [St. Augustine: Serm. li, 13 de Divers. lxiii] on
Ex. 20:14. Now a woman who is not one's own may be of various conditions,
namely either a virgin, or under her father's care, or a harlot, or of
any other description. Therefore it seems that adultery is not a species
of lust distinct from the others.
Objection 2. Further, Jerome says [Contra Jovin. i]: "It matters not for what
reason a man behaves as one demented. Hence Sixtus the Pythagorean says
in his Maxims: He that is insatiable of his wife is an adulterer," and in
like manner one who is over enamored of any woman. Now every kind of lust
includes a too ardent love. Therefore adultery is in every kind of lust:
and consequently it should not be reckoned a species of lust.
Objection 3. Further, where there is the same kind of deformity, there would
seem to be the same species of sin. Now, apparently, there is the same
kind of deformity in seduction and adultery: since in either case a woman
is violated who is under another person's authority. Therefore adultery
is not a determinate species of lust, distinct from the others.
On the contrary, Pope Leo [St. Augustine, De Bono Conjug. iv; Cf.
Append. Grat. ad can. Ille autem. xxxii, qu. 5 says that "adultery is
sexual intercourse with another man or woman in contravention of the
marriage compact, whether through the impulse of one's own lust, or with
the consent of the other party." Now this implies a special deformity of
lust. Therefore adultery is a determinate species of lust.
I answer that, Adultery, as its name implies, "is access to another's
marriage-bed [ad alienum torum]" [Cf. Append. Gratian, ad can. Ille
autem. xxxii, qu. 1. By so doing a man is guilty of a twofold offense
against chastity and the good of human procreation. First, by accession
to a woman who is not joined to him in marriage, which is contrary to the
good of the upbringing of his own children. Secondly, by accession to a
woman who is united to another in marriage, and thus he hinders the good
of another's children. The same applies to the married woman who is
corrupted by adultery. Wherefore it is written (Sirach 23:32,33): "Every
woman . . . that leaveth her husband . . . shall be guilty of sin. For
first she hath been unfaithful to the law of the Most High" (since there
it is commanded: "Thou shalt not commit adultery"); "and secondly, she
hath offended against her husband," by making it uncertain that the
children are his: "thirdly, she hath fornicated in adultery, and hath
gotten children of another man," which is contrary to the good of her
offspring. The first of these, however, is common to all mortal sins,
while the two others belong especially to the deformity of adultery.
Hence it is manifest that adultery is a determinate species of lust,
through having a special deformity in venereal acts.
Reply to Objection 1. If a married man has intercourse with another woman, his
sin may be denominated either with regard to him, and thus it is always
adultery, since his action is contrary to the fidelity of marriage, or
with regard to the woman with whom he has intercourse; and thus sometimes
it is adultery, as when a married man has intercourse with another's
wife; and sometimes it has the character of seduction, or of some other
sin, according to various conditions affecting the woman with whom he has
intercourse: and it has been stated above (1) that the species of lust
correspond to the various conditions of women.
Reply to Objection 2. Matrimony is specially ordained for the good of human
offspring, as stated above (2). But adultery is specially opposed to
matrimony, in the point of breaking the marriage faith which is due
between husband and wife. And since the man who is too ardent a lover of
his wife acts counter to the good of marriage if he use her indecently,
although he be not unfaithful, he may in a sense be called an adulterer;
and even more so than he that is too ardent a lover of another woman.
Reply to Objection 3. The wife is under her husband's authority, as united to him
in marriage: whereas the maid is under her father's authority, as one who
is to be married by that authority. Hence the sin of adultery is contrary
to the good of marriage in one way, and the sin of seduction in another;
wherefore they are reckoned to differ specifically. Of other matters
concerning adultery we shall speak in the Third Part [Supplement,059, 3;
Supplement, 60,62, when we treat of matrimony.
Summa Theologiae II-II, 154, 9
Whether incest is a determinate species of lust?
Objection 1. It would seem that incest is not a determinate species of lust.
For incest ['Incestus' is equivalent to 'in-castus = 'unchaste'] takes
its name from being a privation of chastity. But all kinds of lust are
opposed to chastity. Therefore it seems that incest is not a species of
lust, but is lust itself in general.
Objection 2. Further, it is stated in the Decretals (XXXVI, qu. 1 [Cf.
Append. Grat. ad can. Lex illa]) that "incest is intercourse between a
man and a woman related by consanguinity or affinity." Now affinity
differs from consanguinity. Therefore it is not one but several species
Objection 3. Further, that which does not, of itself, imply a deformity, does
not constitute a determinate species of vice. But intercourse between
those who are related by consanguinity or affinity does not, of itself,
contain any deformity, else it would never have been lawful. Therefore
incest is not a determinate species of lust.
On the contrary, The species of lust are distinguished according to the
various conditions of women with whom a man has unlawful intercourse. Now
incest implies a special condition on the part of the woman, because it
is unlawful intercourse with a woman related by consanguinity or affinity
as stated (Objection 2). Therefore incest is a determinate species of lust.
I answer that, As stated above (A1,6) wherever we find something
incompatible with the right use of venereal actions, there must needs be
a determinate species of lust. Now sexual intercourse with women related
by consanguinity or affinity is unbecoming to venereal union on three
counts. First, because man naturally owes a certain respect to his
parents and therefore to his other blood relations, who are descended in
near degree from the same parents: so much so indeed that among the
ancients, as Valerius Maximus relates [Dict. Fact. Memor. ii, 1, it was
not deemed right for a son to bathe with his father, lest they should
see one another naked. Now from what has been said (142, 4:151,
4), it is evident that in venereal acts there is a certain
shamefulness inconsistent with respect, wherefore men are ashamed of
them. Wherefore it is unseemly that such persons should be united in
venereal intercourse. This reason seems to be indicated (Lev. 18:7) where
we read: "She is thy mother, thou shalt not uncover her nakedness," and
the same is expressed further on with regard to others.
The second reason is because blood relations must needs live in close
touch with one another. Wherefore if they were not debarred from venereal
union, opportunities of venereal intercourse would be very frequent and
thus men's minds would be enervated by lust. Hence in the Old Law [Lev.
18 the prohibition was apparently directed specially to those persons
who must needs live together.
The third reason is, because this would hinder a man from having many
friends: since through a man taking a stranger to wife, all his wife's
relations are united to him by a special kind of friendship, as though
they were of the same blood as himself. Wherefore Augustine says (De Civ.
Dei xv, 16): "The demands of charity are most perfectly satisfied by men
uniting together in the bonds that the various ties of friendship
require, so that they may live together in a useful and becoming amity;
nor should one man have many relationships in one, but each should have
Aristotle adds another reason (2 Polit. ii): for since it is natural
that a man should have a liking for a woman of his kindred, if to this be
added the love that has its origin in venereal intercourse, his love
would be too ardent and would become a very great incentive to lust: and
this is contrary to chastity. Hence it is evident that incest is a
determinate species of lust.
Reply to Objection 1. Unlawful intercourse between persons related to one another
would be most prejudicial to chastity, both on account of the
opportunities it affords, and because of the excessive ardor of love, as
stated in the Article. Wherefore the unlawful intercourse between such
persons is called "incest" antonomastically.
Reply to Objection 2. Persons are related by affinity through one who is related
by consanguinity: and therefore since the one depends on the other,
consanguinity and affinity entail the same kind of unbecomingness.
Reply to Objection 3. There is something essentially unbecoming and contrary to
natural reason in sexual intercourse between persons related by blood,
for instance between parents and children who are directly and
immediately related to one another, since children naturally owe their
parents honor. Hence the Philosopher instances a horse (De Animal. ix,
47) which covered its own mother by mistake and threw itself over a
precipice as though horrified at what it had done, because some animals
even have a natural respect for those that have begotten them. There is
not the same essential unbecomingness attaching to other persons who are
related to one another not directly but through their parents: and, as to
this, becomingness or unbecomingness varies according to custom, and
human or Divine law: because, as stated above (2), sexual intercourse,
being directed to the common good, is subject to law. Wherefore, as
Augustine says (De Civ. Dei xv, 16), whereas the union of brothers and
sisters goes back to olden times, it became all the more worthy of
condemnation when religion forbade it.
Summa Theologiae II-II, 154, 10
Whether sacrilege can be a species of lust?
Objection 1. It would seem that sacrilege cannot be a species of lust. For the
same species is not contained under different genera that are not
subalternated to one another. Now sacrilege is a species of irreligion,
as stated above (99, 2). Therefore sacrilege cannot be reckoned a
species of lust.
Objection 2. Further, the Decretals (XXXVI, qu. 1 [Append. Grat. ad can. Lex
illa]), do not place sacrilege among other sins which are reckoned
species of lust. Therefore it would seem not to be a species of lust.
Objection 3. Further, something derogatory to a sacred thing may be done by
the other kinds of vice, as well as by lust. But sacrilege is not
reckoned a species of gluttony, or of any other similar vice. Therefore
neither should it be reckoned a species of lust.
On the contrary, Augustine says (De Civ. Dei xv, 16) that "if it is
wicked, through covetousness, to go beyond one's earthly bounds, how much
more wicked is it through venereal lust to transgress the bounds of
morals!" Now to go beyond one's earthly bounds in sacred matters is a sin
of sacrilege. Therefore it is likewise a sin of sacrilege to overthrow
the bounds of morals through venereal desire in sacred matters. But
venereal desire pertains to lust. Therefore sacrilege is a species of
I answer that, As stated above (I-II, 18, 6,7), the act of a virtue
or vice, that is directed to the end of another virtue or vice, assumes
the latter's species: thus, theft committed for the sake of adultery,
passes into the species of adultery. Now it is evident that as Augustine
states (De Virgin. 8), the observance of chastity, by being directed to
the worship of God, becomes an act of religion, as in the case of those
who vow and keep chastity. Wherefore it is manifest that lust also, by
violating something pertaining to the worship of God, belongs to the
species of sacrilege: and in this way sacrilege may be accounted a
species of lust.
Reply to Objection 1. Lust, by being directed to another vice as its end, becomes
a species of that vice: and so a species of lust may be also a species of
irreligion, as of a higher genus.
Reply to Objection 2. The enumeration referred to, includes those sins which are
species of lust by their very nature: whereas sacrilege is a species of
lust in so far as it is directed to another vice as its end, and may
coincide with the various species of lust. For unlawful intercourse
between persons mutually united by spiritual relationship, is a sacrilege
after the manner of incest. Ontercourse with a virgin consecrated to God,
inasmuch as she is the spouse of Christ, is sacrilege resembling
adultery. If the maiden be under her father's authority, it will be
spiritual seduction; and if force be employed it will be spiritual rape,
which kind of rape even the civil law punishes more severely than others.
Thus the Emperor Justinian says [Cod. i, iii de Episc. et Cler. 5: "If
any man dare, I will not say to rape, but even to tempt a consecrated
virgin with a view to marriage, he shall be liable to capital punishment."
Reply to Objection 3. Sacrilege is committed on a consecrated thing. Now a
consecrated thing is either a consecrated person, who is desired for
sexual intercourse, and thus it is a kind of lust, or it is desired for
possession, and thus it is a kind of injustice. Sacrilege may also come
under the head of anger, for instance, if through anger an injury be done
to a consecrated person. Again, one may commit a sacrilege by partaking
gluttonously of sacred food. Nevertheless, sacrilege is ascribed more
specially to lust which is opposed to chastity for the observance of
which certain persons are specially consecrated.
Translation by the Fathers of the English Dominican Province,
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(c)Paul Halsall Mar 1996