(b) From the imperfection of the act theft may be only a venial sin, for example, when the thief is a kleptomaniac and steals without advertence, or when he is invincibly ignorant that the thing taken is not his own or is of great value, or from the smallness of the matter involved (e.g., when the thing taken has little value, or the owner is opposed rather to the stealthy manner of taking than to the taking, or is only slightly unwilling to lose the goods).
1895. Theft of a small amount may be a mortal sin (see 187). This may happen: (a) on account of the internal or subjective circumstances, as when the thief intends to steal as much as he can or a large amount here and now, or when he intends to steal a small amount here and new but to keep this up every day until he has stolen a considerable amount, or when a child steals a small sum from its parents and falsely thinks that the theft is gravely sinful in itself; (b) on account of external or objective circumstances, as when the amount taken today is small but constitutes, with amounts previously taken, a large sum, or when the thief foresees serious consequences from his act (e.g., that the person from whom the goods are taken will fall under suspicion and be discharged or arrested). It should be noted, however, that the consequences of the theft do not necessarily make the sin grave precisely as it is a sin of theft (e.g., in the case just given the theft was a venial sin, but the unjust damage was a mortal sin), or even precisely as it is a sin of injustice (e.g., if one steals a picture of small value, foreseeing that the owner will be afflicted beyond measure at the loss, the sin against justice is small, but the sin against charity is mortal).
1896. The determination of the amount that constitutes grave matter in theft or robbery (or in unjust damage) is a very difficult task, because the factors upon which the injury depends are to some extent doubtful and vary in particular cases. Hence, there is a great diversity of opinion among moralists on this subject, and it will frequently be uncertain in an individual case whether a theft is mortally or only venially sinful in itself. But on account of the spiritual and temporal interests that are concerned it is necessary to give at least general rules for direction that will enable one to distinguish between grave and venial theft, and to know when the duty of restitution is serious, when light.
1897. Moralists are in agreement on the following points:
(a) the standard for measuring gravity of matter is not an invariable one, but will differ according to circumstances of times and places. Thus, money has much less purchasing power today than it had before the Civil War, and the same amount will not go so far nor last so long in the United States as in some countries of Europe. Hence, other things being equal, it is less harmful to steal the sum of $10 in 1958 than it was to steal the same sum in 1858, less harmful to steal that amount from an American than to steal its equivalent from a European;
(b) the standard for a particular country and period is to be interpreted morally, not mathematically; for it depends on the opinions or estimates of the prudent, which after all are only approximations and subject to revisions. Hence, it would be absurd to draw such a hard and fast distinction between grave and venial theft—for example, to decide from the amounts alone that he who stole $50 is certainly guilty of mortal sin and fit for hell, while he who stole $49.99 is guilty of venial sin only and not fit for hell. The figures given by moralists for grave matter are averages, and hence they cannot be expected to suit each individual locality or moment or injured person. But, being based on actual conditions, they are serviceable. If a sum stolen is much above or below them, they indicate truly the theological species of the sin; if it is only a little above or below them, they afford a basis for probability, or at least show that there is room for doubt.
1898. Moralists are also at one in measuring the injury of theft by the following considerations:
(a) it should be estimated by the property loss, that is, that theft should be deemed a grave sin which in view of all the circumstances and the common opinion indicts a notable loss on the owner in his property rights. This is a matter of common sense, for every one can see that it is a very different thing to steal a cent and to steal $100.
(b) it should be estimated by the personal injury, that is, by the unwillingness of the proprietor to suffer the loss. This is also clear, since the unwillingness of the proprietor is one of the ingredients of theft, as was explained above in the definition, and everyone will readily grant that an amount which would be notable if stolen from a stranger, would not be notable if stolen from an indulgent parent.
1899. There are two opinions about the estimation of the property loss.