Summa summae S. Thomae, Tomus III

[The possessor in good faith is he who invincibly does not know that the thing possessed by him belongs to another. In civil law, he is called a possessor in good faith who possesses as if he were owner, under a title translative of ownership, whose defects he does not know. Whence his good faith ceases as soon as the defects of the title are uncovered¹ . — It is evident that such a possessor injures the right of the true owner only by an injustice merely material, but not formal.]

Note 1° for the present and following articles that, when we come to the part of restitution, not only the thing received but also the fruits of the thing are distinguished (but a fruit is the utility gathered from a thing, after expenses have been deducted), into fruits of four kinds, namely merely natural, merely industrial, mixed, and civil.

Merely natural fruits are those which nature bears spontaneously, with no human labor cooperating, or at least only light labor, such as the grass of meadows, the fruits of trees, the offspring of animals, etc. Merely industrial fruits are, on the contrary, those which the labor or industry of men alone produces, not the nature of the thing, although the latter can concur as an instrument of the working and industrious man. Such is the gain from trafficking in money, wine, grain and similar things sterile of themselves; likewise a work of art wrought with another's instrument is reckoned the fruit of industry, not of the instrument.

Mixed fruits are those for producing which the nature of the thing and the industry of man concur equally, or nearly equally; for here what differs little seems to differ nothing, such as crops, wine, oil, butter, cheese, etc.

Civil fruits are so called not because they are properly fruits, but because in law they are reckoned after the manner of fruits. Such are the prices of things let out, as houses, ships, beasts of burden, fisheries, hunts, etc. They can be reduced to mixed fruits, because to those there concurs not only industry, but the thing itself, horse, house, etc. Where there is doubt of what kind fruits are, recourse must be had to the judgment of the judge or of a prudent and learned man.

Note 2°. But, since in the restitution of fruits the expenses are usually deducted (for fruit, as I already said, is the utility from a thing after expenses deducted), expenses must be distinguished of three kinds. Some are necessary, without which the thing would either have perished or become worse : as the repair of a falling building, food for animals, etc. Certain ones are useful, which although they are not necessary for the conservation of the thing, nevertheless conduce to its betterment and increase its return, as plantings of trees, conduits of water, the addition of a mill, etc. Others are voluptuary or voluntary, which do not increase the fruit, but adorn its appearance only, as fountains, marblings, paintings, statues, etc. On account of these the thing indeed may be valued at more, yet because it does not yield more fruits, therefore they are called voluptuary or voluntary expenses. Under the character of expense, however, must be understood the labor and industry of the possessor.

Note 3°. Finally improvement, like deterioration, is twofold : one intrinsic, as when the thing changed in itself becomes better or worse, v. g., if a colt become a horse, if a lean ox become fat, or on the contrary a fat one become lean; extrinsic, when the thing unchanged in itself is nevertheless valued at more or less, on account of the abundance or scarcity of buyers or goods, or by authority of law, v. g., grain which yesterday was worth three today is worth four, or on the contrary.

[Principles. 1° A possessor in good faith ought not to grow rich from the thing of another. So all say² . — Excepted is the case where the thing has already been legitimately prescribed : in which case he does not grow rich from the thing of another, but from a thing which by force of law has been made his own.

2° A possessor in good faith ought, per se, to be kept unharmed, that is, as he can acquire nothing from the thing of another, so he ought to lose nothing, because he is not at fault. — I said, « per se, » because, in a case of conflict between possessor and owner, the owner of the existing thing is stronger in right; laws however, on account of the common good, sometimes favor the owner of the thing, sometimes the possessor.]

These things noted,

I say 1° : The possessor in good faith is held to restore insofar as he possesses from the thing of another and its fruits or profit : so that the quantity of the thing possessed and of its existing fruits, or of the profit thence arising, be the measure of the restitution to be made; because this is required and suffices for restoring equality according to the form of commutative justice. From this general assertion and rule I deduce the following conclusions, first concerning the thing, then concerning the fruits. Whence

I say 2° : The possessor in good faith, as soon as he understands that the thing he possesses belongs to another, is held to restore it while it still exists, in whole or in part, unless perchance he has prescribed it within legitimate time.

The reason is plain, because he who has beyond what is his own ought to be deprived of it and it given to him who lacks it; otherwise justice is not saved, and he becomes an unjust detainer³ .

But if he consumed the thing, or it perished by chance or even through his fault, he is held to restore nothing, except that by which he was made richer by it. — The first part is plain, because he is not bound by reason of a thing received, which he no longer has, nor by reason of an unjust acquisition or alienation, because he possessed in good faith. And although perhaps he sinned by squandering it prodigally or otherwise, he did not nevertheless sin against commutative justice, since he disposed of a thing which he invincibly thought was his own. — The second part is also plain; because that by which he was made richer succeeds in place of the thing, and it is against natural law that anyone grow rich with injury to another, according to this rule of law 48, in 6° : « No one ought to be enriched with the injustice or loss of another. » Hence

I say 3° : The possessor in good faith is held to restore all natural, mixed and civil fruits still existing, unless perchance he has prescribed them, however, with the necessary and useful expenses deducted, and with the estimation of the industry and labor.

The reason is that they are fruits of the thing; but the thing fructifies to its own owner.

Nor does it stand in the way that mixed and civil fruits are not merely fruits of the thing; for by the very fact that the part corresponding to the expenses and the estimation of labor and industry is deducted, the whole that remains over is fruit of the thing. Nor again does it stand in the way that perhaps the thing would not have so fructified with the owner; for that pertains to the good fortune of the owner, because wherever the thing fructifies, it fructifies to its owner.

[Indeed, attending to natural law alone, all fruits of the thing, except industrial ones, ought to be rendered to the owner, because the thing, wherever it may be, fructifies to its owner. Nevertheless, if positive law decree otherwise, it can more probably be stood upon; for it must reasonably be presumed that such is the force of the law, that it transfers the dominion of the fruits to the possessor, on account of the public good, that it may remove from the midst the inextricable difficulties and complaints which would very frequently be raised concerning the nature and quantity of the fruits which the owner would claim⁴ . Furthermore Gallican law decrees that the fruits pertain indiscriminately to the possessor in good faith⁵ . So likewise Austrian, Italian and Prussian law⁶ . Therefore.

Except the case where, by some legal disposition, the ceasing profit would have to be compensated to the owner. Thus by Austrian law

the finder of a lost thing not yet prescribed owes the owner appearing, besides the thing or its price, also to pay back the profit received thence⁷ .

But if the fruits no longer exist, consumed in any way whatever, he is held only to that by which he was made richer, as is plain from the first conclusion and is found in law, L. Item veniunt, § Propter haec, ff de petitione haereditatis, lib. V, tit. 3.

I said : « With the necessary and useful expenses deducted, and the estimation of labor and industry, » namely necessary and useful. Otherwise the owner would have more than he ought to have, and would grow rich from another's. And it is found in law, L. Fructus, ff Soluto matrimonio, where it is said : « Fruits are not understood, unless the outlays have been deducted. »

Moreover it is to be noted concerning useful expenses, which plainly make the thing better and more useful, that the owner of the thing is not held to pay back to the possessor in good faith the value of the improvement itself, but only of the expenses, provided however they do not exceed the value of the improvement. So L. In fundo, ff de rei vindic. lib. III, tit. 1.

As to voluptuary expenses or improvements, authors agree that they can be removed by the possessor in good faith, if they can be separated from the thing without its destruction or deterioration, such as clocks, pictures, doors, windows, etc.; or if they have not come onto the ground by implantation, as trees (and this is also true of the possessor in bad faith). But if they cannot be removed without deterioration of the thing, or have accrued to the ground by implantation, it seems more probable that the owner of the thing is not held to those expenses, at least in the forum of conscience; for it does not seem equitable that he pay expenses which he would not have wished to make and which bring him no utility. And L. Ex duobus 27, ff de negotiis gestis, lib. III, tit. 5 favors this.

I say 4° : As to merely industrial fruits, the possessor in good faith is held to restore nothing whatever of them (which is also true of the possessor in bad faith), even if he was made richer thereby. This is common opinion. The reason is that the fruits belong to him to whom belongs the fruitful cause. Yet the thing of another, being sterile, as is supposed, is not the cause of these fruits, but the industry of the possessor alone. Therefore. — So all say.

[You will ask 1° to what the possessor in good faith is bound, if he has given away the thing of another to someone.

I answer. He is bound to nothing, if he was in no way made richer from the thing; otherwise he ought to restore to the owner that by which he was enriched. This twofold solution is drawn from the principles enunciated above. But once the error is detected, the donor of the thing of another is bound, if he can easily do so, either to admonish the donee, that he render the thing to its owner, or the owner, that he may be able to reclaim his thing. This obligation arises from the general precept of charity, and moreover, as it seems, from the law of commutative justice, since the author of an injustice, even merely material, is held to repair it if he can do so without his own notable inconvenience.

You will ask 2° to what the possessor in good faith is bound, if he has sold gratuitously accepted property belonging to another.

I answer 1° In case of eviction, he is bound to pay back the price to the buyer; otherwise he would grow rich from the thing of another.

2° Outside the case of eviction, namely when the thing cannot be recovered by the owner, whether because the last possessor consumed it, or because he no longer appears, the seller, according to the common opinion, owes the whole price received from the buyer back to the owner. The reason is that from the whole of that price he was truly made richer, and the owner unjustly despoiled of his thing suffered an equivalent damage. Furthermore equity does not tolerate that one man, with the loss of another, be enriched from his goods. Whence the owner must be made whole from the profit which the seller received and to which he had no right.

Certain ones nevertheless entirely free the seller, because against him the owner has no recourse. But this does not seem true; for the seller would grow rich from the thing of another. it would not be safe, in this case, to depart from the common opinion ⁸.

You will ask 3° to what the possessor in good faith is bound who sold the thing of another, which afterward perished in the hands of the buyer.

I answer 1° If he had the thing under an onerous title, v. g., because he bought it, it is more probable he is bound to nothing. For indeed : 1° he is not bound by reason of the thing, since he no longer has it; 2° nor by reason of the damage, since he is not the cause why the thing perished.

2° If he had the thing under a gratuitous title, he is held to restore the price by which he was made richer through the sale. This is the common opinion. But, to whom is it to be restored? The theologians disagree. Some probably say it is to be restored to the buyer: both because the thing perishes to its owner; and because the sale, being of the thing of another, was invalid, and therefore the buyer in good faith has a right to recover his money. Others, more probably, because more equitably, as it seems to us, teach that it is to be restored to the owner: both because the thing did not perish absolutely, but exists equivalently in the price received; and because the sale, which was null, the thing perishing, harms the buyer no more than a valid sale. But since the former opinion is not lacking in probability, the seller would not need to be disturbed if he had paid back the price to the buyer. — It is to be noted that, if positive law determines to whom the restoration is to be made, the law is to be stood upon, because it validly determines the dominion, lest difficulties arise thence ⁹.

You will ask 4° what is to be done if, after it is recognized that the thing belongs to another, the owner cannot be found.

I answer this case is to be solved from the principles enunciated above concerning a thing found. You received, v. g., through blameless error, more than was owed, from one you know not. If you could not find the owner, the money given beyond what is owed must be held as a thing abandoned, and its dominion is acquired by the first occupant.

Note that, if the possessor in good faith be culpably in delay of restoring, he is constituted in bad faith, and therefore is held to compensate the damage ensuing from the delay.]