Summa Th. I-II EN Qu.72 a.5
1445
Objection: 1. It would seem that the division of sins according to their debt of punishment diversifies their species; for instance, when sin is divided into "mortal" and "venial." For things which are infinitely apart, cannot belong to the same species, nor even to the same genus. But venial and mortal sin are infinitely apart, since temporal punishment is due to venial sin, and eternal punishment to mortal sin; and the measure of the punishment corresponds to the gravity of the fault, according to Dt 25,2: "According to the measure of the sin shall the measure be also of the stripes be." Therefore venial and mortal sins are not of the same genus, nor can they be said to belong to the same species.
2. Further, some sins are mortal in virtue of their species [*"Ex genere," genus in this case denoting the species], as murder and adultery; and some are venial in virtue of their species, as in an idle word, and excessive laughter. Therefore venial and mortal sins differ specifically.
3. Further, just as a virtuous act stands in relation to its reward, so does sin stand in relation to punishment. But the reward is the end of the virtuous act. Therefore punishment is the end of sin. Now sins differ specifically in relation to their ends, as stated above (Article [1], ad 1). Therefore they are also specifically distinct according to the debt of punishment.
On the contrary Those things that constitute a species are prior to the species, e.g. specific differences. But punishment follows sin as the effect thereof. Therefore sins do not differ specifically according to the debt of punishment.
I answer that In things that differ specifically we find a twofold difference: the first causes the diversity of species, and is not to be found save in different species, e.g. "rational" and "irrational," "animate," and "inanimate": the other difference is consequent to specific diversity; and though, in some cases, it may be consequent to specific diversity, yet, in others, it may be found within the same species; thus "white" and "black" are consequent to the specific diversity of crow and swan, and yet this difference is found within the one species of man.We must therefore say that the difference between venial and mortal sin, or any other difference is respect of the debt of punishment, cannot be a difference constituting specific diversity. For what is accidental never constitutes a species; and what is outside the agent's intention is accidental (Phys. ii, text. 50). Now it is evident that punishment is outside the intention of the sinner, wherefore it is accidentally referred to sin on the part of the sinner. Nevertheless it is referred to sin by an extrinsic principle, viz. the justice of the judge, who imposes various punishments according to the various manners of sin. Therefore the difference derived from the debt of punishment, may be consequent to the specific diversity of sins, but cannot constitute it.Now the difference between venial and mortal sin is consequent to the diversity of that inordinateness which constitutes the notion of sin. For inordinateness is twofold, one that destroys the principle of order, and another which, without destroying the principle of order, implies inordinateness in the things which follow the principle: thus, in an animal's body, the frame may be so out of order that the vital principle is destroyed; this is the inordinateness of death; while, on the other hand, saving the vital principle, there may be disorder in the bodily humors; and then there is sickness. Now the principle of the entire moral order is the last end, which stands in the same relation to matters of action, as the indemonstrable principle does to matters of speculation (Ethic. vii, 8). Therefore when the soul is so disordered by sin as to turn away from its last end, viz. God, to Whom it is united by charity, there is mortal sin; but when it is disordered without turning away from God, there is venial sin. For even as in the body, the disorder of death which results from the destruction of the principle of life, is irreparable according to nature, while the disorder of sickness can be repaired by reason of the vital principle being preserved, so it is in matters concerning the soul. Because, in speculative matters, it is impossible to convince one who errs in the principles, whereas one who errs, but retains the principles, can be brought back to the truth by means of the principles. Likewise in practical matters, he who, by sinning, turns away from his last end, if we consider the nature of his sin, falls irreparably, and therefore is said to sin mortally and to deserve eternal punishment: whereas when a man sins without turning away from God, by the very nature of his sin, his disorder can be repaired, because the principle of the order is not destroyed; wherefore he is said to sin venially, because, to wit, he does not sin so as to deserve to be punished eternally.
Reply to Objection: 1. Mortal and venial sins are infinitely apart as regards what they "turn away from," not as regards what they "turn to," viz. the object which specifies them. Hence nothing hinders the same species from including mortal and venial sins; for instance, in the species "adultery" the first movement is a venial sin; while an idle word, which is, generally speaking, venial, may even be a mortal sin.
2. From the fact that one sin is mortal by reason of its species, and another venial by reason of its species, it follows that this difference is consequent to the specific difference of sins, not that it is the cause thereof. And this difference may be found even in things of the same species, as stated above.
3. The reward is intended by him that merits or acts virtually; whereas the punishment is not intended by the sinner, but, on the contrary, is against his will. Hence the comparison fails.
1446
Objection: 1. It would seem that sins of commission and omission differ specifically. For "offense" and "sin" are condivided with one another (Ep 2,1), where it is written: "When you were dead in your offenses and sins," which words a gloss explains, saying: "'Offenses,' by omitting to do what was commanded, and 'sins,' by doing what was forbidden." Whence it is evident that "offenses" here denotes sins of omission; while "sin" denotes sins of commission. Therefore they differ specifically, since they are contrasted with one another as different species.
2. Further, it is essential to sin to be against God's law, for this is part of its definition, as is clear from what has been said (Question [71], Article [6]). Now in God's law, the affirmative precepts, against which is the sin of omission, are different from the negative precepts, against which is the sin of omission. Therefore sins of omission and commission differ specifically.
3. Further, omission and commission differ as affirmation and negation. Now affirmation and negation cannot be in the same species, since negation has no species; for "there is neither species nor difference of non-being," as the Philosopher states (Phys. iv, text. 67). Therefore omission and commission cannot belong to the same species.
On the contrary Omission and commission are found in the same species of sin. For the covetous man both takes what belongs to others, which is a sin of commission; and gives not of his own to whom he should give, which is a sin of omission. Therefore omission and commission do not differ specifically.
I answer that There is a twofold difference in sins; a material difference and a formal difference: the material difference is to be observed in the natural species of the sinful act; while the formal difference is gathered from their relation to one proper end, which is also their proper object. Hence we find certain acts differing from one another in the material specific difference, which are nevertheless formally in the same species of sin, because they are directed to the one same end: thus strangling, stoning, and stabbing come under the one species of murder, although the actions themselves differ specifically according to the natural species. Accordingly, if we refer to the material species in sins of omission and commission, they differ specifically, using species in a broad sense, in so far as negation and privation may have a species. But if we refer to the formal species of sins of omission and commission, they do not differ specifically, because they are directed to the same end, and proceed from the same motive. For the covetous man, in order to hoard money, both robs, and omits to give what he ought, and in like manner, the glutton, to satiate his appetite, both eats too much and omits the prescribed fasts. The same applies to other sins: for in things, negation is always founded on affirmation, which, in a manner, is its cause. Hence in the physical order it comes under the same head, that fire gives forth heat, and that it does not give forth cold.
Reply to Objection: 1. This division in respect of commission and omission, is not according to different formal species, but only according to material species, as stated.
2. In God's law, the necessity for various affirmative and negative precepts, was that men might be gradually led to virtue, first by abstaining from evil, being induced to this by the negative precepts, and afterwards by doing good, to which we are induced by the affirmative precepts. Wherefore the affirmative and negative precepts do not belong to different virtues, but to different degrees of virtue; and consequently they are not of necessity, opposed to sins of different species. Moreover sin is not specified by that from which it turns away, because in this respect it is a negation or privation, but by that to which it turns, in so far as sin is an act. Consequently sins do not differ specifically according to the various precepts of the Law.
3. This objection considers the material diversity of sins. It must be observed, however, that although, properly speaking, negation is not in a species, yet it is allotted to a species by reduction to the affirmation on which it is based.
1447
Objection: 1. It would seem that sins are unfittingly divided into sins of thought, word, and deed. For Augustine (De Trin. xii, 12) describes three stages of sin, of which the first is "when the carnal sense offers a bait," which is the sin of thought; the second stage is reached "when one is satisfied with the mere pleasure of thought"; and the third stage, "when consent is given to the deed." Now these three belong to the sin of thought. Therefore it is unfitting to reckon sin of thought as one kind of sin.
2. Further, Gregory (Moral. iv, 25) reckons four degrees of sin; the first of which is "a fault hidden in the heart"; the second, "when it is done openly"; the third, "when it is formed into a habit"; and the fourth, "when man goes so far as to presume on God's mercy or to give himself up to despair": where no distinction is made between sins of deed and sins of word, and two other degrees of sin are added. Therefore the first division was unfitting.
3. Further, there can be no sin of word or deed unless there precede sin of thought. Therefore these sins do not differ specifically. Therefore they should not be condivided with one another.
On the contrary Jerome in commenting on Ez 43,23: "The human race is subject to three kinds of sin, for when we sin, it is either by thought, or word, or deed."
I answer that Things differ specifically in two ways: first, when each has the complete species; thus a horse and an ox differ specifically: secondly, when the diversity of species is derived from diversity of degree in generation or movement: thus the building is the complete generation of a house, while the laying of the foundations, and the setting up of the walls are incomplete species, as the Philosopher declares (Ethic. x, 4); and the same can apply to the generation of animals. Accordingly sins are divided into these three, viz. sins of thought, word, and deed, not as into various complete species: for the consummation of sin is in the deed, wherefore sins of deed have the complete species; but the first beginning of sin is its foundation, as it were, in the sin of thought; the second degree is the sin of word, in so far as man is ready to break out into a declaration of his thought; while the third degree consists in the consummation of the deed. Consequently these three differ in respect of the various degrees of sin. Nevertheless it is evident that these three belong to the one complete species of sin, since they proceed from the same motive. For the angry man, through desire of vengeance, is at first disturbed in thought, then he breaks out into words of abuse, and lastly he goes on to wrongful deeds; and the same applies to lust and to any other sin.
Reply to Objection: 1. All sins of thought have the common note of secrecy, in respect of which they form one degree, which is, however, divided into three stages, viz. of cogitation, pleasure, and consent.
2. Sins of words and deed are both done openly, and for this reason Gregory (Moral. iv, 25) reckons them under one head: whereas Jerome (in commenting on Ez 43,23) distinguishes between them, because in sins of word there is nothing but manifestation which is intended principally; while in sins of deed, it is the consummation of the inward thought which is principally intended, and the outward manifestation is by way of sequel. Habit and despair are stages following the complete species of sin, even as boyhood and youth follow the complete generation of a man.
3. Sin of thought and sin of word are not distinct from the sin of deed when they are united together with it, but when each is found by itself: even as one part of a movement is not distinct from the whole movement, when the movement is continuous, but only when there is a break in the movement.
1448
Objection: 1. It would seem that excess and deficiency do not diversify the species of sins. For excess and deficiency differ in respect of more and less. Now "more" and "less" do not diversify a species. Therefore excess and deficiency do not diversify the species of sins.
2. Further, just as sin, in matters of action, is due to straying from the rectitude of reason, so falsehood, in speculative matters, is due to straying from the truth of the reality. Now the species of falsehood is not diversified by saying more or less than the reality. Therefore neither is the species of sin diversified by straying more or less from the rectitude of reason.
3. Further, "one species cannot be made out of two," as Porphyry declares [*Isagog.; cf. Arist. Metaph. i]. Now excess and deficiency are united in one sin; for some are at once illiberal and wasteful---illiberality being a sin of deficiency, and prodigality, by excess. Therefore excess and deficiency do not diversify the species of sins.
On the contrary Contraries differ specifically, for "contrariety is a difference of form," as stated in Metaph. x, text. 13,14. Now vices that differ according to excess and deficiency are contrary to one another, as illiberality to wastefulness. Therefore they differ specifically.
I answer that While there are two things in sin, viz. the act itself and its inordinateness, in so far as sin is a departure from the order of reason and the Divine law, the species of sin is gathered, not from its inordinateness, which is outside the sinner's intention, as stated above (Article [1]), but one the contrary, from the act itself as terminating in the object to which the sinner's intention is directed. Consequently wherever we find a different motive inclining the intention to sin, there will be a different species of sin. Now it is evident that the motive for sinning, in sins by excess, is not the same as the motive for sinning, in sins of deficiency; in fact, they are contrary to one another, just as the motive in the sin of intemperance is love for bodily pleasures, while the motive in the sin of insensibility is hatred of the same. Therefore these sins not only differ specifically, but are contrary to one another.
Reply to Objection: 1. Although "more" and "less" do not cause diversity of species, yet they are sometimes consequent to specific difference, in so far as they are the result of diversity of form; thus we may say that fire is lighter than air. Hence the Philosopher says (Ethic. viii, 1) that "those who held that there are no different species of friendship, by reason of its admitting of degree, were led by insufficient proof." In this way to exceed reason or to fall short thereof belongs to sins specifically different, in so far as they result from different motives.
2. It is not the sinner's intention to depart from reason; and so sins of excess and deficiency do not become of one kind through departing from the one rectitude of reason. On the other hand, sometimes he who utters a falsehood, intends to hide the truth, wherefore in this respect, it matters not whether he tells more or less. If, however, departure from the truth be not outside the intention, it is evident that then one is moved by different causes to tell more or less; and in this respect there are different kinds of falsehood, as is evident of the "boaster," who exceeds in telling untruths for the sake of fame, and the "cheat," who tells less than the truth, in order to escape from paying his debts. This also explains how some false opinions are contrary to one another.
3. One may be prodigal and illiberal with regard to different objects: for instance one may be illiberal [*Cf. II-II 119,1, ad 1] in taking what one ought not: and nothing hinders contraries from being in the same subject, in different respects.
1449
Objection: 1. It would seem that vices and sins differ in respect of different circumstances. For, as Dionysius says (Div. Nom. iv), "evil results from each single defect." Now individual defects are corruptions of individual circumstances. Therefore from the corruption of each circumstance there results a corresponding species of sin.
2. Further, sins are human acts. But human acts sometimes take their species from circumstances, as stated above (Question [18], Article [10]). Therefore sins differ specifically according as different circumstances are corrupted.
3. Further, diverse species are assigned to gluttony, according to the words contained in the following verse:'Hastily, sumptuously, too much, greedily, daintily.' Now these pertain to various circumstances, for "hastily" means sooner than is right; "too much," more than is right, and so on with the others. Therefore the species of sin is diversified according to the various circumstances.
On the contrary The Philosopher says (Ethic. iii, 7; iv, 1) that "every vice sins by doing more than one ought, and when one ought not"; and in like manner as to the other circumstances. Therefore the species of sins are not diversified in this respect.
I answer that As stated above (Article [8]), wherever there is a special motive for sinning, there is a different species of sin, because the motive for sinning is the end and object of sin. Now it happens sometimes that although different circumstances are corrupted, there is but one motive: thus the illiberal man, for the same motive, takes when he ought not, where he ought not, and more than he ought, and so on with the circumstances, since he does this through an inordinate desire of hoarding money: and in such cases the corruption of different circumstances does not diversify the species of sins, but belongs to one and the same species.Sometimes, however, the corruption of different circumstances arises from different motives: for instance that a man eat hastily, may be due to the fact that he cannot brook the delay in taking food, on account of a rapid exhaustion of the digestive humors; and that he desire too much food, may be due to a naturally strong digestion; that he desire choice meats, is due to his desire for pleasure in taking food. Hence in such matters, the corruption of different circumstances entails different species of sins.
Reply to Objection: 1. Evil, as such, is a privation, and so it has different species in respect of the thing which the subject is deprived, even as other privations. But sin does not take its species from the privation or aversion, as stated above (Article [1]), but from turning to the object of the act.
2. A circumstance never transfers an act from one species to another, save when there is another motive.
3. In the various species of gluttony there are various motives, as stated.
1460
We must now consider the comparison of one sin with another: under which head there are ten points of inquiry:
(1) Whether all sins and vices are connected with one another?
(2) Whether all are equal?
(3) Whether the gravity of sin depends on its object?
(4) Whether it depends on the excellence of the virtue to which it is opposed?
(5) Whether carnal sins are more grievous than spiritual sins?
(6) Whether the gravity of sins depends on their causes?
(7) Whether it depends on their circumstances?
(8) Whether it depends on how much harm ensues?
(9) Whether on the position of the person sinned against?
(10) Whether sin is aggravated by reason of the excellence of the person sinning?
1461
Objection: 1. It would seem that all sins are connected. For it is written (Jc 2,10): "Whosoever shall keep the whole Law, but offend in one point, is become guilty of all." Now to be guilty of transgressing all the precepts of Law, is the same as to commit all sins, because, as Ambrose says (De Parad. viii), "sin is a transgression of the Divine law, and disobedience of the heavenly commandments." Therefore whoever commits one sin is guilty of all.
2. Further, each sin banishes its opposite virtue. Now whoever lacks one virtue lacks them all, as was shown above (Question [65], Article [1]). Therefore whoever commits one sin, is deprived of all the virtues. Therefore whoever commits one sin, is guilty of all sins.
3. Further, all virtues are connected, because they have a principle in common, as stated above (Question [65], Articles [1],2). Now as the virtues have a common principle, so have sins, because, as the love of God, which builds the city of God, is the beginning and root of all the virtues, so self-love, which builds the city of Babylon, is the root of all sins, as Augustine declares (De Civ. Dei xiv, 28). Therefore all vices and sins are also connected so that whoever has one, has them all.
On the contrary Some vices are contrary to one another, as the Philosopher states (Ethic. ii, 8). But contraries cannot be together in the same subject. Therefore it is impossible for all sins and vices to be connected with one another.
I answer that The intention of the man who acts according to virtue in pursuance of his reason, is different from the intention of the sinner in straying from the path of reason. For the intention of every man acting according to virtue is to follow the rule of reason, wherefore the intention of all the virtues is directed to the same end, so that all the virtues are connected together in the right reason of things to be done, viz. prudence, as stated above (Question [65], Article [1]). But the intention of the sinner is not directed to the point of straying from the path of reason; rather is it directed to tend to some appetible good whence it derives its species. Now these goods, to which the sinner's intention is directed when departing from reason, are of various kinds, having no mutual connection; in fact they are sometimes contrary to one another. Since, therefore, vices and sins take their species from that to which they turn, it is evident that, in respect of that which completes a sin's species, sins are not connected with one another. For sin does not consist in passing from the many to the one, as is the case with virtues, which are connected, but rather in forsaking the one for the many.
Reply to Objection: 1. James is speaking of sin, not as regards the thing to which it turns and which causes the distinction of sins, as stated above (Question [72], Article [1]), but as regards that from which sin turns away, in as much as man, by sinning, departs from a commandment of the law. Now all the commandments of the law are from one and the same, as he also says in the same passage, so that the same God is despised in every sin; and in this sense he says that whoever "offends in one point, is become guilty of all," for as much as, by committing one sin, he incurs the debt of punishment through his contempt of God, which is the origin of all sins.
2. As stated above (Question [71], Article [4]), the opposite virtue is not banished by every act of sin; because venial sin does not destroy virtue; while mortal sin destroys infused virtue, by turning man away from God. Yet one act, even of mortal sin, does not destroy the habit of acquired virtue; though if such acts be repeated so as to engender a contrary habit, the habit of acquired virtue is destroyed, the destruction of which entails the loss of prudence, since when man acts against any virtue whatever, he acts against prudence, without which no moral virtue is possible, as stated above (Question [58], Article [4]; Question [65], Article [1]). Consequently all the moral virtues are destroyed as to the perfect and formal being of virtue, which they have in so far as they partake of prudence, yet there remain the inclinations to virtuous acts, which inclinations, however, are not virtues. Nevertheless it does not follow that for this reason man contracts all vices of sins---first, because several vices are opposed to one virtue, so that a virtue can be destroyed by one of them, without the others being present; secondly, because sin is directly opposed to virtue, as regards the virtue's inclination to act, as stated above (Question [71], Article [1]). Wherefore, as long as any virtuous inclinations remain, it cannot be said that man has the opposite vices or sins.
3. The love of God is unitive, in as much as it draws man's affections from the many to the one; so that the virtues, which flow from the love of God, are connected together. But self-love disunites man's affections among different things, in so far as man loves himself, by desiring for himself temporal goods, which are various and of many kinds: hence vices and sins, which arise from self-love, are not connected together.
1462
Objection: 1. It would seem that all sins are equal. Because sin is to do what is unlawful. Now to do what is unlawful is reproved in one and the same way in all things. Therefore sin is reproved in one and the same way. Therefore one sin is not graver than another.
2. Further, every sin is a transgression of the rule of reason, which is to human acts what a linear rule is in corporeal things. Therefore to sin is the same as to pass over a line. But passing over a line occurs equally and in the same way, even if one go a long way from it or stay near it, since privations do not admit of more or less. Therefore all sins are equal.
3. Further, sins are opposed to virtues. But all virtues are equal, as Cicero states (Paradox. iii). Therefore all sins are equal.
On the contrary Our Lord said to Pilate (Jn 19,11): "He that hath delivered me to thee, hath the greater sin," and yet it is evident that Pilate was guilty of some sin. Therefore one sin is greater than another.
I answer that The opinion of the Stoics, which Cicero adopts in the book on Paradoxes (Paradox. iii), was that all sins are equal: from which opinion arose the error of certain heretics, who not only hold all sins to be equal, but also maintain that all the pains of hell are equal. So far as can be gathered from the words of Cicero the Stoics arrived at their conclusion through looking at sin on the side of the privation only, in so far, to wit, as it is a departure from reason; wherefore considering simply that no privation admits of more or less, they held that all sins are equal. Yet, if we consider the matter carefully, we shall see that there are two kinds of privation. For there is a simple and pure privation, which consists, so to speak, in "being" corrupted; thus death is privation of life, and darkness is privation of light. Such like privations do not admit of more or less, because nothing remains of the opposite habit; hence a man is not less dead on the first day after his death, or on the third or fourth days, than after a year, when his corpse is already dissolved; and, in like manner, a house is no darker if the light be covered with several shades, than if it were covered by a single shade shutting out all the light. There is, however, another privation which is not simple, but retains something of the opposite habit; it consists in "becoming" corrupted rather than in "being" corrupted, like sickness which is a privation of the due commensuration of the humors, yet so that something remains of that commensuration, else the animal would cease to live: and the same applies to deformity and the like. Such privations admit of more or less on the part of what remains or the contrary habit. For it matters much in sickness or deformity, whether one departs more or less from the due commensuration of humors or members. The same applies to vices and sins: because in them the privation of the due commensuration of reason is such as not to destroy the order of reason altogether; else evil, if total, destroys itself, as stated in Ethic. iv, 5. For the substance of the act, or the affection of the agent could not remain, unless something remained of the order of reason. Therefore it matters much to the gravity of a sin whether one departs more or less from the rectitude of reason: and accordingly we must say that sins are not all equal.
Reply to Objection: 1. To commit sin is lawful on account of some inordinateness therein: wherefore those which contain a greater inordinateness are more unlawful, and consequently graver sins.
2. This argument looks upon sin as though it were a pure privation.
3. Virtues are proportionately equal in one and the same subject: yet one virtue surpasses another in excellence according to its species; and again, one man is more virtuous than another, in the same species of virtue, as stated above (Question [66], Articles [1],2). Moreover, even if virtues were equal, it would not follow that vices are equal, since virtues are connected, and vices or sins are not.
1463
Objection: 1. It would seem that the gravity of sins does not vary according to their objects. Because the gravity of a sin pertains to its mode or quality: whereas the object is the matter of the sin. Therefore the gravity of sins does not vary according to their various objects.
2. Further, the gravity of a sin is the intensity of its malice. Now sin does not derive its malice from its proper object to which it turns, and which is some appetible good, but rather from that which it turns away from. Therefore the gravity of sins does not vary according to their various objects.
3. Further, sins that have different objects are of different kinds. But things of different kinds cannot be compared with one another, as is proved in Phys. vii, text. 30, seqq. Therefore one sin is not graver than another by reason of the difference of objects.
On the contrary Sins take their species from their objects, as was shown above (Question [72], Article [1]). But some sins are graver than others in respect of their species, as murder is graver than theft. Therefore the gravity of sins varies according to their objects.
I answer that As is clear from what has been said (Question [71], Article [5]), the gravity of sins varies in the same way as one sickness is graver than another: for just as the good of health consists in a certain commensuration of the humors, in keeping with an animal's nature, so the good of virtue consists in a certain commensuration of the human act in accord with the rule of reason. Now it is evident that the higher the principle the disorder of which causes the disorder in the humors, the graver is the sickness: thus a sickness which comes on the human body from the heart, which is the principle of life, or from some neighboring part, is more dangerous. Wherefore a sin must needs be so much the graver, as the disorder occurs in a principle which is higher in the order of reason. Now in matters of action the reason directs all things in view of the end: wherefore the higher the end which attaches to sins in human acts, the graver the sin. Now the object of an act is its end, as stated above (Question [72], Article [3], ad 2); and consequently the difference of gravity in sins depends on their objects. Thus it is clear that external things are directed to man as their end, while man is further directed to God as his end. Wherefore a sin which is about the very substance of man, e.g. murder, is graver than a sin which is about external things, e.g. theft; and graver still is a sin committed directly against God, e.g. unbelief, blasphemy, and the like: and in each of these grades of sin, one sin will be graver than another according as it is about a higher or lower principle. And forasmuch as sins take their species from their objects, the difference of gravity which is derived from the objects is first and foremost, as resulting from the species.
Reply to Objection: 1. Although the object is the matter about which an act is concerned, yet it has the character of an end, in so far as the intention of the agent is fixed on it, as stated above (Question [72], Article [3], ad 2). Now the form of a moral act depends on the end, as was shown above (Question [72], Article [6]; Question [18], Article [6]).
2. From the very fact that man turns unduly to some mutable good, it follows that he turns away from the immutable Good, which aversion completes the nature of evil. Hence the various degrees of malice in sins must needs follow the diversity of those things to which man turns.
3. All the objects of human acts are related to one another, wherefore all human acts are somewhat of one kind, in so far as they are directed to the last end. Therefore nothing prevents all sins from being compared with one another.
Summa Th. I-II EN Qu.72 a.5