(a) He is guilty of thoughtlessness, then, who fails to do what he can to judge rightly about his duty; nor is he excused if he leaves the whole matter to God, for it is temptation of God to expect that He will provide when man does not do his own part (Prov., iv. 25).
(b) He is not guilty of thoughtlessness who has not the opportunity of judging, or who lacks sufficient knowledge, or who is taken unawares; nor is he guilty of temptation of God, if in such difficulties he commits all to Providence. Thus, when various nations were gathered together to fight against Juda, King Josaphat prayed: “As we know not what to do, we can only turn our eyes to Thee” (II Par., xx. 12). And Our Lord promised special help to the disciples for cases of need when they were unable to help themselves (Matt., x. 19).
1669. The Sin of Inconstancy.—The sin of changeableness or inconstancy is committed when, owing to anger, jealousy or other inordinate passion, the reason repudiates things that had been rightly decided on and fails to act on judgments that had been rightly made (Is., xxxvii. 3). From inconstancy result incontinence (i.e., instability in the face of pleasure) and effeminacy (i.e., instability in the face of sadness).
1670. Causes of the Sins of Haste, Thoughtlessness, and Inconstancy.—(a) Every inordinate desire brings on these sins by diverting the mind from a good to an evil object. Experience shows that the avaricious, the ambitious, the angry, the jealous, etc., do not listen to reason, but act imprudently: “Where envying and contention is, there is inconstancy” (James, iii. 16).
(b) Desire of pleasure, especially of venereal pleasure, is most fatal to prudence by extinguishing the judgment of reason. The intellect is immaterial and is occupied with abstract truth, whereas sensual delights are immersed in the material and sensible. Hence, carnal sins are more injurious to prudence than spiritual sins. The sensual man not merely does not listen to reason, but he does not even hear it. Venus steals away the reason, said Aristotle, and this truth is well exemplified in King Solomon.
1671. The Sin of Negligence.—The sin of negligence is opposed to carefulness or diligence, and consists in the failure of the reason to direct properly an act, or some circumstance of an act, to which one is obliged.
(a) Negligence is a general sin in the sense that it has no special matter of its own, such as a passion to be moderated (as is the case with temperance and fortitude) or an action to be regulated (as is the case with justice). The acts of reason should extend to every kind of matter, and hence a person may be negligent (and likewise inconstant, thoughtless, hasty) with reference to any kind of action or passion.
(b) It is properly a special sin, as being the opposite of carefulness, which is a special act of prudence.
1672. Negligence is distinct from the following sins: (a) from laziness and lukewarmness, which are defects of the external act, while negligence is a defect of the internal act (see 1326, 1327); (b) from sins of omission, which pertain to external acts and are results of negligence, and are opposed to some other virtue than prudence (e.g., negligence in paying debts is against justice); (c) from inconstancy, which fails to command an act to which one is bound, as though one were impeded, while negligence fails because there is a want of promptness in the will. The inconstant man is easily diverted from his course; the negligent man is slow in getting under way.
1673. The Sinfulness of Negligence.—(a) It is a mortal sin when some act or circumstance necessary for salvation is omitted on its account (e.g., when a debtor puts off from day to day the payment of a bill, and in consequence causes a great injury), or when it proceeds from contempt or preference of the creature to God. (b) It is a venial sin when the act or circumstance omitted is not necessary for salvation (e.g., when a judge causes a slight injustice by reason of his procrastination), or when it proceeds from a want of fervor.