Summa summae S. Thomae, Tomus III

Dico 1° : For debts arising from unjust acquisition, detention, or damage, restitution must be made at the expense of the debtor, in the place where the owner would have possessed the thing if it had not been taken away. This is the common opinion.

Proof., because the owner ought not to suffer loss through the fault of the debtor. Yet he would suffer it, if he had to recover his property at his own expense. Therefore.

It is confirmed. He who is bound to an end is bound to the means necessary and proportionate for attaining that end. Now the debtor is bound to such a restitution as keeps the owner indemnified; and this cannot come about without expense. Therefore he is bound to those expenses.

Understand this, however, of expenses that do not much exceed the value of the thing; and therefore I said, « proportionate means; » because otherwise the restitution would be judged more burdensome, and therefore morally impossible, as I shall say below. Make an exception when from the omission of restitution there follows for the owner some other damage greatly exceeding the expenses ¹.

[Yet there must be deducted the expenses which the owner would have had to make to preserve the thing, or to bring it to the place where it must now be given back; because otherwise the owner would grow rich from another's property.

If, moreover, the restitution ought to be judged morally impossible on account of the extraordinary expenses necessary for sending the thing back, the bad-faith detainer cannot turn it to his own use, unless he is himself in grave necessity, since he may not grow rich from another's property; but from the presumed will of the owner he must distribute it to the poor, or spend it on other pious causes — unless he can sell the thing and send the price to the owner ².

How great, then, the expenses are that the unjust detainer is bound to make in order to restore the thing itself is not easily determined. Some bind him to expenses of any amount whatever; others only to those that equal the value of the thing; others to expenses twice as great as the debt. Since the general rule stands fixed, judgment must be made in each individual case, taking account both of the value of the thing and of the respective condition of debtor and creditor; and if the expenses appear evidently disproportionate, then either the restitution must be deferred until it can be made less burdensomely, or, if the thing is of great importance, it must be sold, so that the price may be sent to the owner, or, if its value is slight, the thing itself or its price must be spent on pious works.]

I say 2° : For debts arising from a thing received, restitution must be made in the place where the things are held; and if they must be transferred to the owner, this must be done at his expense; because no one without his own fault ought to suffer loss.

As regards debts from contract, it is certain that one must stand by the agreement expressly made in the contract, as to place and expenses; but if no agreement was expressly made, the tacit agreement must be gathered from the nature of the contract, the custom of the place, and other circumstances.

I say 3° : When the owner himself designated the messenger through whom he wished his property restored to him, he incurs the loss if the thing perishes by accident or through the fault of the messenger, under whatever title the thing is owed to him, and whether the same thing is to be given back or another; because in such a case the messenger bears the person of the owner, and what is handed over to him is reckoned as handed over to the owner. Similarly, if he left the debtor the freedom to choose whichever messenger he wished, provided he choose one who is regarded as trustworthy; because then the debtor has performed all that the owner required, and consequently all that the debtor himself owed.

I say 4° : If a thing owed solely by the title of a thing received perishes — even though sufficient diligence was used on the part of the debtor, that is, if he chose a messenger who is regarded as trustworthy, and sent it back by ways not regarded as dangerous — whether it perish by accident or through the fault of the messenger, it does not perish to the debtor, but to the owner, and consequently the debtor is exempted from further restitution; because this thing is the owner's, and a thing perishes to its owner, especially since no fault intervened on the part of the debtor. From this you will gather, conversely, that if the debtor is at fault, because he either chose a messenger who was not regarded as trustworthy, or sent the thing back by dangerous ways, it perishes to him, and he is held to further restitution.

I say 5° : A thing owed by reason of unjust acquisition, detention, or damage, however it may perish — outside the case of the third conclusion, whether the same thing is to be given back or not — perishes to the debtor himself, who in consequence is bound to further restitution. This is the more common and more probable opinion; because, if that thing were to perish by accident in the hands of the debtor, it would perish to him, as we said above according to the common opinion, since the unjust detainer is bound even for fortuitous chance, having taken upon himself every peril of the thing. Hence the common axiom does not avail here: « Res perit domino, » the thing perishes to the owner. Therefore it also perishes to the debtor himself, if it perish in the hands of a messenger whom he chose.

I say 6° : A thing owed from contract, if the same thing in number is to be given back, as in commodatum, hire, or deposit, perishes to the owner, provided sufficient diligence was used on the part of the debtor. If another thing in number is to be given back, as in a mutuum loan, in the price of goods, etc., it perishes to the debtor, even if he used sufficient diligence: because, in the first case, the thing is the owner's and remains under his dominion; in the second case, however, it is the debtor's. Moreover, as the thing cries out for its owner, so also it perishes to the owner. Hence, if you send back a horse given in commodatum together with money given in mutuum, and both perish on the way, the horse perishes to the owner, and the money to you.