Section — Prümmer, Manuale Theologiae Moralis
§ 2. At What Time Restitution Is To Be Made
237. Principle. Restitution owed is to be made as soon as it can be made, morally speaking.107
The reason is that it is not lawful to retain another's thing when the owner is reasonably unwilling. But the owner is reasonably unwilling that another possessor retain the thing longer than he can restore it here and now. Hence it is a grave sin, without cause, to defer for a notable time the restitution of grave matter. It is otherwise, however, if the delay is slight. What constitutes a notable time cannot be determined with certainty. If notable damage arises to the legitimate owner from an unjust delay, e.g., risk to the principal or gain or interest ceasing, then it seems to be a grave sin.
But he who for a just cause defers restitution does not indeed sin; he is nevertheless then held to repair all the damage which he foresees the creditor will suffer therefrom. Thus at least if the obligation of restitution arose from a delict.108
He who has the will not to restore and does not revoke it commits only one sin, although he adverts to the obligation of restoring more frequently; this sin, however, is aggravated the longer that depraved purpose endures.109
Note. The confessor ought to insist that restitution be made as quickly as is morally possible, and especially he should not permit restitution to be deferred until death. Moreover, he should urge that at least partial restitution be made if total restitution is impossible. If the penitent culpably omitted the restitution promised in preceding confessions, he ordinarily cannot be absolved before he has actually restored.
107 Cf. St. Thomas, S. theol. 2, 2, q. 62, a. 8.
108 Cf. St. Alphonsus, l. c. n. 680.
109 Cf. above, I, n. 378.