SLOTH. - "It is a tendency to idleness or at least to negligence and torpor in acting" (A. Tanquerey, Compendio di teologia ascetica e mistica, 7th ed., Rome 1927, no. 884). It is sometimes a morbid disposition, arising from a poor state of health, and must be treated by a physician; ordinarily, however, it is moral in character and is caused by a weak will that dreads and refuses effort. Understood in this way, sloth, rather than being opposed to one particular virtue, is opposed to all the virtues, inasmuch as their exercise involves difficulty and therefore demands effort.
The sin of sloth, insofar as it is opposed to the general law of work, is ordinarily not grave; it becomes grave, however, when it is habitual and when it causes the omission or neglect of particular grave obligations. Sloth is one of the most serious obstacles to perfection, both because it renders life more or less sterile, like the field of the lazy man of which Sacred Scripture speaks (cf. Prov. 24:30-34), and, above all, because it allows temptations to become more vigorous and insistent. It is well known, in fact, that when the higher faculties are inactive, the lower are freer to follow their instincts, and then "idleness teaches much malice" (Eccl. 23:29). One understands, therefore, how sloth can create a grave danger to eternal salvation itself. The slothful man indeed deserved the severe condemnation of the servant who does not trade his talents (Mt. 25:24-30), and of the tree that bears no fruit (Mt. 3:10).
Remedies against sloth are: deep convictions about the necessity and the intimate satisfaction of work done with love; awareness of the grave consequences that flow from sloth; and the continued and methodical effort that gives the slothful man the satisfaction of a life usefully employed.