Summa Theologica, by St. Thomas Aquinas, [1947], at sacred-texts.com
We must now consider the vices opposed to the joy of charity. This joy is either about the Divine good, and then its contrary is sloth, or about our neighbor's good, and then its contrary is envy. Wherefore we must consider (1) Sloth and (2) Envy.
Under the first head there are four points of inquiry:
(1) Whether sloth is a sin?
(2) Whether it is a special vice?
(3) Whether it is a mortal sin?
(4) Whether it is a capital sin?
Objection 1: It would seem that sloth is not a sin. For we are neither praised nor blamed for our passions, according to the Philosopher (Ethic. ii, 5). Now sloth is a passion, since it is a kind of sorrow, according to Damascene (De Fide Orth. ii, 14), and as we stated above (FS, Q[35], A[8] ). Therefore sloth is not a sin.
Objection 2: Further, no bodily failing that occurs at fixed times is a sin. But sloth is like this, for Cassian says (De Instit. Monast. x, [*De Institutione Caeobiorum]): "The monk is troubled with sloth chiefly about the sixth hour: it is like an intermittent fever, and inflicts the soul of the one it lays low with burning fires at regular and fixed intervals." Therefore sloth is not a sin.
Objection 3: Further, that which proceeds from a good root is, seemingly, no sin. Now sloth proceeds from a good root, for Cassian says (De Instit. Monast. x) that "sloth arises from the fact that we sigh at being deprived of spiritual fruit, and think that other monasteries and those which are a long way off are much better than the one we dwell in": all of which seems to point to humility. Therefore sloth is not a sin.
Objection 4: Further, all sin is to be avoided, according to Ecclus. 21:2: "Flee from sins as from the face of a serpent." Now Cassian says (De Instit. Monast. x): "Experience shows that the onslaught of sloth is not to be evaded by flight but to be conquered by resistance." Therefore sloth is not a sin.
On the contrary, Whatever is forbidden in Holy Writ is a sin. Now such is sloth [acedia]: for it is written (Ecclus. 6:26): "Bow down thy shoulder, and bear her," namely spiritual wisdom, "and be not grieved [acedieris] with her bands." Therefore sloth is a sin.
I answer that, Sloth, according to Damascene (De Fide Orth. ii, 14) is an oppressive sorrow, which, to wit, so weighs upon man's mind, that he wants to do nothing; thus acid things are also cold. Hence sloth implies a certain weariness of work, as appears from a gloss on Ps. 106:18, "Their soul abhorred all manner of meat," and from the definition of some who say that sloth is a "sluggishness of the mind which neglects to begin good."
Now this sorrow is always evil, sometimes in itself, sometimes in its effect. For sorrow is evil in itself when it is about that which is apparently evil but good in reality, even as, on the other hand, pleasure is evil if it is about that which seems to be good but is, in truth, evil. Since, then, spiritual good is a good in very truth, sorrow about spiritual good is evil in itself. And yet that sorrow also which is about a real evil, is evil in its effect, if it so oppresses man as to draw him away entirely from good deeds. Hence the Apostle (2 Cor. 2:7) did not wish those who repented to be "swallowed up with overmuch sorrow."
Accordingly, since sloth, as we understand it here, denotes sorrow for spiritual good, it is evil on two counts, both in itself and in point of its effect. Consequently it is a sin, for by sin we mean an evil movement of the appetite, as appears from what has been said above (Q[10], A[2]; FS, Q[74], A[4]).
Reply to Objection 1: Passions are not sinful in themselves; but they are blameworthy in so far as they are applied to something evil, just as they deserve praise in so far as they are applied to something good. Wherefore sorrow, in itself, calls neither for praise nor for blame: whereas moderate sorrow for evil calls for praise, while sorrow for good, and again immoderate sorrow for evil, call for blame. It is in this sense that sloth is said to be a sin.
Reply to Objection 2: The passions of the sensitive appetite may either be venial sins in themselves, or incline the soul to mortal sin. And since the sensitive appetite has a bodily organ, it follows that on account of some bodily transmutation a man becomes apt to commit some particular sin. Hence it may happen that certain sins may become more insistent, through certain bodily transmutations occurring at certain fixed times. Now all bodily effects, of themselves, dispose one to sorrow; and thus it is that those who fast are harassed by sloth towards mid-day, when they begin to feel the want of food, and to be parched by the sun's heat.
Reply to Objection 3: It is a sign of humility if a man does not think too much of himself, through observing his own faults; but if a man contemns the good things he has received from God, this, far from being a proof of humility, shows him to be ungrateful: and from such like contempt results sloth, because we sorrow for things that we reckon evil and worthless. Accordingly we ought to think much of the goods of others, in such a way as not to disparage those we have received ourselves, because if we did they would give us sorrow.
Reply to Objection 4: Sin is ever to be shunned, but the assaults of sin should be overcome, sometimes by flight, sometimes by resistance; by flight when a continued thought increases the incentive to sin, as in lust; for which reason it is written (1 Cor. 6:18): "Fly fornication"; by resistance, when perseverance in the thought diminishes the incentive to sin, which incentive arises from some trivial consideration. This is the case with sloth, because the more we think about spiritual goods, the more pleasing they become to us, and forthwith sloth dies away.
Objection 1: It would seem that sloth is not a special vice. For that which is common to all vices does not constitute a special kind of vice. But every vice makes a man sorrowful about the opposite spiritual good: for the lustful man is sorrowful about the good of continence, and the glutton about the good of abstinence. Since then sloth is sorrow for spiritual good, as stated above (A[1]), it seems that sloth is not a special sin.
Objection 2: Further, sloth, through being a kind of sorrow, is opposed to joy. Now joy is not accounted one special virtue. Therefore sloth should not be reckoned a special vice.
Objection 3: Further, since spiritual good is a general kind of object, which virtue seeks, and vice shuns, it does not constitute a special virtue or vice, unless it be determined by some addition. Now nothing, seemingly, except toil, can determine it to sloth, if this be a special vice; because the reason why a man shuns spiritual goods, is that they are toilsome, wherefore sloth is a kind of weariness: while dislike of toil, and love of bodily repose seem to be due to the same cause, viz. idleness. Hence sloth would be nothing but laziness, which seems untrue, for idleness is opposed to carefulness, whereas sloth is opposed to joy. Therefore sloth is not a special vice.
On the contrary, Gregory (Moral. xxxi, 45) distinguishes sloth from the other vices. Therefore it is a special vice.
I answer that, Since sloth is sorrow for spiritual good, if we take spiritual good in a general way, sloth will not be a special vice, because, as stated above (FS, Q[71], A[1]), every vice shuns the spiritual good of its opposite virtue. Again it cannot be said that sloth is a special vice, in so far as it shuns spiritual good, as toilsome, or troublesome to the body, or as a hindrance to the body's pleasure, for this again would not sever sloth from carnal vices, whereby a man seeks bodily comfort and pleasure.
Wherefore we must say that a certain order exists among spiritual goods, since all the spiritual goods that are in the acts of each virtue are directed to one spiritual good, which is the Divine good, about which there is a special virtue, viz. charity. Hence it is proper to each virtue to rejoice in its own spiritual good, which consists in its own act, while it belongs specially to charity to have that spiritual joy whereby one rejoices in the Divine good. In like manner the sorrow whereby one is displeased at the spiritual good which is in each act of virtue, belongs, not to any special vice, but to every vice, but sorrow in the Divine good about which charity rejoices, belongs to a special vice, which is called sloth. This suffices for the Replies to the Objections.
Objection 1: It would seem that sloth is not a mortal sin. For every mortal sin is contrary to a precept of the Divine Law. But sloth seems contrary to no precept, as one may see by going through the precepts of the Decalogue. Therefore sloth is not a mortal sin.
Objection 2: Further, in the same genus, a sin of deed is no less grievous than a sin of thought. Now it is not a mortal sin to refrain in deed from some spiritual good which leads to God, else it would be a mortal sin not to observe the counsels. Therefore it is not a mortal sin to refrain in thought from such like spiritual works. Therefore sloth is not a mortal sin.
Objection 3: Further, no mortal sin is to be found in a perfect man. But sloth is to be found in a perfect man: for Cassian says (De Instit. Caenob. x, l) that "sloth is well known to the solitary, and is a most vexatious and persistent foe to the hermit." Therefore sloth is not always a mortal sin.
On the contrary, It is written (2 Cor. 7:20): "The sorrow of the world worketh death." But such is sloth; for it is not sorrow "according to God," which is contrasted with sorrow of the world. Therefore it is a mortal sin.
I answer that, As stated above (FS, Q[88], AA[1],2), mortal sin is so called because it destroys the spiritual life which is the effect of charity, whereby God dwells in us. Wherefore any sin which by its very nature is contrary to charity is a mortal sin by reason of its genus. And such is sloth, because the proper effect of charity is joy in God, as stated above (Q[28], A[1]), while sloth is sorrow about spiritual good in as much as it is a Divine good. Therefore sloth is a mortal sin in respect of its genus. But it must be observed with regard to all sins that are mortal in respect of their genus, that they are not mortal, save when they attain to their perfection. Because the consummation of sin is in the consent of reason: for we are speaking now of human sins consisting in human acts, the principle of which is the reason. Wherefore if the sin be a mere beginning of sin in the sensuality alone, without attaining to the consent of reason, it is a venial sin on account of the imperfection of the act. Thus in the genus of adultery, the concupiscence that goes no further than the sensuality is a venial sin, whereas if it reach to the consent of reason, it is a mortal sin. So too, the movement of sloth is sometimes in the sensuality alone, by reason of the opposition of the flesh to the spirit, and then it is a venial sin; whereas sometimes it reaches to the reason, which consents in the dislike, horror and detestation of the Divine good, on account of the flesh utterly prevailing over the spirit. In this case it is evident that sloth is a mortal sin.
Reply to Objection 1: Sloth is opposed to the precept about hallowing the Sabbath day. For this precept, in so far as it is a moral precept, implicitly commands the mind to rest in God: and sorrow of the mind about the Divine good is contrary thereto.
Reply to Objection 2: Sloth is not an aversion of the mind from any spiritual good, but from the Divine good, to which the mind is obliged to adhere. Wherefore if a man is sorry because someone forces him to do acts of virtue that he is not bound to do, this is not a sin of sloth; but when he is sorry to have to do something for God's sake.
Reply to Objection 3: Imperfect movements of sloth are to be found in holy men, but they do not reach to the consent of reason.
Objection 1: It would seem that sloth ought not to be accounted a capital vice. For a capital vice is one that moves a man to sinful acts, as stated above (Q[34], A[5]). Now sloth does not move one to action, but on the contrary withdraws one from it. Therefore it should not be accounted a capital sin.
Objection 2: Further, a capital sin is one to which daughters are assigned. Now Gregory (Moral. xxxi, 45) assigns six daughters to sloth, viz. "malice, spite, faint-heartedness, despair, sluggishness in regard to the commandments, wandering of the mind after unlawful things." Now these do not seem in reality to arise from sloth. For "spite" is, seemingly the same as hatred, which arises from envy, as stated above (Q[34], A[6]); "malice" is a genus which contains all vices, and, in like manner, a "wandering" of the mind after unlawful things is to be found in every vice; "sluggishness" about the commandments seems to be the same as sloth, while "faint-heartedness" and "despair" may arise from any sin. Therefore sloth is not rightly accounted a capital sin.
Objection 3: Further, Isidore distinguishes the vice of sloth from the vice of sorrow, saying (De Summo Bono ii, 37) that in so far as a man shirks his duty because it is distasteful and burdensome, it is sorrow, and in so far as he is inclined to undue repose, it is sloth: and of sorrow he says that it gives rise to "spite, faint-heartedness, bitterness, despair," whereas he states that from sloth seven things arise, viz. "idleness, drowsiness, uneasiness of the mind, restlessness of the body, instability, loquacity, curiosity." Therefore it seems that either Gregory or Isidore has wrongly assigned sloth as a capital sin together with its daughters.
On the contrary, The same Gregory (Moral. xxxi, 45) states that sloth is a capital sin, and has the daughters aforesaid.
I answer that, As stated above (FS, Q[84], AA[3],4), a capital vice is one which easily gives rise to others as being their final cause. Now just as we do many things on account of pleasure, both in order to obtain it, and through being moved to do something under the impulse of pleasure, so again we do many things on account of sorrow, either that we may avoid it, or through being exasperated into doing something under pressure thereof. Wherefore, since sloth is a kind of sorrow, as stated above (A[2]; FS, Q[85], A[8]), it is fittingly reckoned a capital sin.
Reply to Objection 1: Sloth by weighing on the mind, hinders us from doing things that cause sorrow: nevertheless it induces the mind to do certain things, either because they are in harmony with sorrow, such as weeping, or because they are a means of avoiding sorrow.
Reply to Objection 2: Gregory fittingly assigns the daughters of sloth. For since, according to the Philosopher (Ethic. viii, 5,6) "no man can be a long time in company with what is painful and unpleasant," it follows that something arises from sorrow in two ways: first, that man shuns whatever causes sorrow; secondly, that he passes to other things that give him pleasure: thus those who find no joy in spiritual pleasures, have recourse to pleasures of the body, according to the Philosopher (Ethic. x, 6). Now in the avoidance of sorrow the order observed is that man at first flies from unpleasant objects, and secondly he even struggles against such things as cause sorrow. Now spiritual goods which are the object of the sorrow of sloth, are both end and means. Avoidance of the end is the result of "despair," while avoidance of those goods which are the means to the end, in matters of difficulty which come under the counsels, is the effect of "faint-heartedness," and in matters of common righteousness, is the effect of "sluggishness about the commandments." The struggle against spiritual goods that cause sorrow is sometimes with men who lead others to spiritual goods, and this is called "spite"; and sometimes it extends to the spiritual goods themselves, when a man goes so far as to detest them, and this is properly called "malice." In so far as a man has recourse to eternal objects of pleasure, the daughter of sloth is called "wandering after unlawful things." From this it is clear how to reply to the objections against each of the daughters: for "malice" does not denote here that which is generic to all vices, but must be understood as explained. Nor is "spite" taken as synonymous with hatred, but for a kind of indignation, as stated above: and the same applies to the others.
Reply to Objection 3: This distinction between sorrow and sloth is also given by Cassian (De Instit. Caenob. x, 1). But Gregory more fittingly (Moral. xxxi, 45) calls sloth a kind of sorrow, because, as stated above (A[2]), sorrow is not a distinct vice, in so far as a man shirks a distasteful and burdensome work, or sorrows on account of any other cause whatever, but only in so far as he is sorry on account of the Divine good, which sorrow belongs essentially to sloth; since sloth seeks undue rest in so far as it spurns the Divine good. Moreover the things which Isidore reckons to arise from sloth and sorrow, are reduced to those mentioned by Gregory: for "bitterness" which Isidore states to be the result of sorrow, is an effect of "spite." "Idleness" and "drowsiness" are reduced to "sluggishness about the precepts": for some are idle and omit them altogether, while others are drowsy and fulfil them with negligence. All the other five which he reckons as effects of sloth, belong to the "wandering of the mind after unlawful things." This tendency to wander, if it reside in the mind itself that is desirous of rushing after various things without rhyme or reason, is called "uneasiness of the mind," but if it pertains to the imaginative power, it is called "curiosity"; if it affect the speech it is called "loquacity"; and in so far as it affects a body that changes place, it is called "restlessness of the body," when, to wit, a man shows the unsteadiness of his mind, by the inordinate movements of members of his body; while if it causes the body to move from one place to another, it is called "instability"; or "instability" may denote changeableness of purpose.