Objection 1: It would seem that one may ask for some other kind of consideration for money lent. For everyone may lawfully seek to indemnify himself. Now sometimes a man suffers loss through lending money. Therefore he may lawfully ask for or even exact something else besides the money lent.
Obj. 2: Further, as stated in Ethic. v, 5, one is in duty bound by a point of honor, to repay anyone who has done us a favor. Now to lend money to one who is in straits is to do him a favor for which he should be grateful. Therefore the recipient of a loan, is bound by a natural debt to repay something. Now it does not seem unlawful to bind oneself to an obligation of the natural law. Therefore it is not unlawful, in lending money to anyone, to demand some sort of compensation as condition of the loan.
Obj. 3: Further, just as there is real remuneration, so is there verbal remuneration, and remuneration by service, as a gloss says on Isa. 33:15, "Blessed is he that shaketh his hands from all bribes [*Vulg.: 'Which of you shall dwell with everlasting burnings? . . . He that shaketh his hands from all bribes.']." Now it is lawful to accept service or praise from one to whom one has lent money. Therefore in like manner it is lawful to accept any other kind of remuneration.
Obj. 4: Further, seemingly the relation of gift to gift is the same as of loan to loan. But it is lawful to accept money for money given. Therefore it is lawful to accept repayment by loan in return for a loan granted.
Obj. 5: Further, the lender, by transferring his ownership of a sum of money removes the money further from himself than he who entrusts it to a merchant or craftsman. Now it is lawful to receive interest for money entrusted to a merchant or craftsman. Therefore it is also lawful to receive interest for money lent.
Obj. 6: Further, a man may accept a pledge for money lent, the use of which pledge he might sell for a price: as when a man mortgages his land or the house wherein he dwells. Therefore it is lawful to receive interest for money lent.
Obj. 7: Further, it sometimes happens that a man raises the price of his goods under guise of loan, or buys another's goods at a low figure; or raises his price through delay in being paid, and lowers his price that he may be paid the sooner. Now in all these cases there seems to be payment for a loan of money: nor does it appear to be manifestly illicit. Therefore it seems to be lawful to expect or exact some consideration for money lent.
On the contrary, Among other conditions requisite in a just man it is stated (Ezech. 18:17) that he "hath not taken usury and increase."
I answer that, According to the Philosopher (Ethic. iv, 1), a thing is reckoned as money "if its value can be measured by money." Consequently, just as it is a sin against justice, to take money, by tacit or express agreement, in return for lending money or anything else that is consumed by being used, so also is it a like sin, by tacit or express agreement to receive anything whose price can be measured by money. Yet there would be no sin in receiving something of the kind, not as exacting it, nor yet as though it were due on account of some agreement tacit or expressed, but as a gratuity: since, even before lending the money, one could accept a gratuity, nor is one in a worse condition through lending.
On the other hand it is lawful to exact compensation for a loan, in respect of such things as are not appreciated by a measure of money, for instance, benevolence, and love for the lender, and so forth.