We have referred above, when dealing with the legitimacy of commercial profits, to the difficulty which was felt in admitting the justice of compensation for risk, on account of the Gregorian Decretal on the subject. The same decree gave rise to the same difficulty in connection with the justification of a recompense for _periculum sortis_. There was a serious dispute about the actual wording of the decree, and even those who agreed as to its wording differed as to its interpretation.[1] The justice of the title was, however, admitted by Scotus, who said that it was lawful to stipulate for recompense when both the principal and surplus were in danger of being lost[2]; by Carletus;[3] and by Nider.[4] The question, however, was still hotly disputed at the end of the fifteenth century, and was finally settled in favour of the admission of the title as late as 1645.[5] [Footnote 1: _Ibid._] [Footnote 2: Cleary, _op. cit._, p. 117.] [Footnote 3: _Summa Angelica Usura_, i. 38.] [Footnote 4: _De Cont. Merc._, iii. 15.] [Footnote 5: Cleary, _op. cit._, p. 117.] § 6. _Other Cases in which more than the Loan could be repaid_. We have now discussed the extrinsic titles--_poena conventionalis, damnum emergens, lucrum cessans_, and _periculum sortis_. There were other grounds also, which cannot be reduced to the classification of extrinsic titles, on which more than the amount of the loan might be justly returned to the lender. In the first place, the lender might justly receive anything that the borrower chose to pay over and above the loan, voluntarily as a token of gratitude. 'Repayment for a favour may be done in two ways,' says Aquinas. 'In one way, as a debt of justice; and to such a debt a man may be bound by a fixed contract; and its amount is measured according to the favour received. Wherefore the borrower of money, or any such thing the use of which is its consumption, is not bound to repay more than he received in loan; and consequently it is against justice if he is obliged to pay back more. In another way a man's obligation to repayment for favour received is based on a debt of friendship, and the nature of this debt depends more on the feeling with which the favour was conferred than on the question of the favour itself. This debt does not carry with it a civil obligation, involving a kind of necessity that would exclude the spontaneous nature of such a repayment.'[1] [Footnote 1: II. ii. 78, 2, ad. 2.]