Summa Theologiae Moralis, vol. I: De Principiis

S. Th. II-II, q. 35; de Malo q. 11.

511. Sloth is sadness about a spiritual good especially divine; it is torpor, coldness, languor, tepidity, weariness about spiritual things, because they impede quiet and bodily delight. Hence sloth prefers to do nothing, and thence is born flight, horror, detestation of spiritual goods. Which sadness is sin, both 1) by reason of the object: for to be saddened about evil is good, but to be saddened about that which apparently is evil but truly is good, is sin, because good does not deserve to be saddened about; — and 2) by reason of the effect: for it withdraws man from due works (cf. tr. on Charity).

512. Sloth is twofold: 1) that by which we are saddened about the good of any virtue whatsoever; and this is not a special sin even if it is done because of the bodily labor adjoined, but it is a circumstance of every sin, because every vice flees the opposite spiritual good even inasmuch as it impedes bodily quiet. Whence it is mortal or venial according as the sin of which it is the circumstance is grave or light; — 2) that by which we are saddened about a spiritual good by excellence to which all other things are ordered, namely about the divine good, not in itself but inasmuch as it is internal to us and pertains to us and seems evil to us, as e.g. about blessedness or about the friendship of God, and about the means to it, namely about the sacraments, the grace of God, good works, the divine precepts, etc. inasmuch as they require labor. This is a special sin, because it has a special object, and is directly contrary to a special act of a special virtue: for it is opposed to the joy about the divine good in which charity delights. Whence of itself it is mortal sin, because according to its proper notion it is opposed to charity: for just as envy is mortal sin, because it is saddened about the good of neighbor in which charity rejoices, so a fortiori sloth, which is saddened about the divine good. It can however be venial, if it is not perfectly deliberate, or even when it is concerned with goods not necessary for salvation.

513. From special sloth six sins arise. — From sadness indeed it happens that man flees those things about which he is saddened, indeed that he fights them, and that he passes to other things about which he delights. From sloth man flees the divine goods: 1) the last end, eternal salvation or the hoped-for divine good, which is done by despair; he flees also 2) the spiritual good to be done or the means to the end common and ordinary, which is torpor about precepts; 3) he flees arduous means, as e.g. of counsel, by pusillanimity. — He fights 4) the contrary spiritual goods, detesting them, which is called malice; or also 5) he fights priests and God-fearing men who induce others to spiritual goods, and is indignant against them; and this is rancor. — Finally 6) because of sadness he passes to exterior delightful things, in which the carnal mind delights, and this is wandering of mind about illicit things.

514. Observation. — Several other sins arise from the capital vices; what we have handed down are those which more frequently and more immediately arise from them, and which therefore are called their daughters. Others, through these as means, are not so frequently born from them, as envy from vainglory, anger from envy, and sloth from anger, and from sloth avarice, gluttony, and lust. Thus Gregory the Great, Mor. bk. XXXI, c. 45 (P. L. LXXVI, 620-622).