In 1274 Gregory X., in the Council of Lyons, ordained that no community, corporation, or individual should permit foreign usurers to hire houses, but that they should expel them from their territory; and the disobedient, if prelates, were to have their lands put under interdict, and, if laymen, to be visited by their ordinary with ecclesiastical censures.[1] By a further canon he ordained that the wills of usurers who did not make restitution should be invalid.[2] This brought usury definitely within the jurisdiction of the ecclesiastical courts.[3] In 1311 the Council of Vienne declared all secular legislation in favour of usury null and void, and branded as heresy the belief that usury was not sinful.[4] The precise extent and interpretation of this decree have given rise to a considerable amount of discussion,[5] which need not detain us here, because by that time the whole question of usury had come under the treatment of the great scholastic writers, whose teaching is more particularly the subject matter of the present essay. [Footnote 1: _Liber Sextus_, v. 5, 1.] [Footnote 2: _Ibid._, c. 2.] [Footnote 3: Ashley, _op. cit._, vol. i. pt. i. p. 150.] [Footnote 4: _Clementinarum_, v. 5, 1.] [Footnote 5: Cleary, _op. cit._, pp. 74-8.] Even as late as the first half of the thirteenth century there was no serious discussion of usury by the theologians. William of Paris, Alexander of Hales, and Albertus Magnus simply pronounced it sinful on account of the texts in the Old and New Testaments, which we have quoted above.[1] It was Aquinas who really put the teaching on usury upon the new foundation, which was destined to support it for so many hundred years, and which even at the present day appeals to many sympathetic and impartial inquirers. Mr. Lecky apologises for the obscurity of his account of the argument of Aquinas, but adds that the confusion is chiefly the fault of the latter;[2] but the fact that Mr. Lecky failed to grasp the meaning of the argument should not lead one to conclude that the argument itself was either confused or illogical. The fact that it for centuries remained the basis of the Catholic teaching on the subject is a sufficient proof that its inherent absurdity did not appear apparent to many students at least as gifted as Mr. Lecky. We shall quote the article of Aquinas at some length, because it was universally accepted by all the theologians of the fourteenth and fifteenth centuries, with whose opinions we are concerned in this essay. To quote later writings is simply to repeat in different words the conclusions at which Aquinas arrived.[3] [Footnote 1: Jourdain, _op. cit._, p. 15.] [Footnote 2: _Rise and Influence, of Rationalism in Europe_, vol. ii. p. 261.] [Footnote 3: Endemann, _Studien_, vol. i. p. 17.]