and then goes on to defend the proposition that, "Usury is forbidden by natural, by divine, and by human law. The first is proved thus. Natural law, as far as its first principles are concerned, is contained in the decalogue; but usury is prohibited in the decalogue, inasmuch as theft is prohibited; and this is the opinion of the Master of the Sentences, of St. Bonaventura, of St. Thomas and of a host of others: for by the name of theft in the Law all unlawful taking of another's goods is prohibited; but usury is an unlawful, etc." For a proof of usury's being contrary to divine law he cites Ex. xxii.25, and Deut. xxiii.29; and from the New Testament Luke vi.34. "The third assertion is proved thus. Usury is forbidden by human law: The First Council of Nice in Canon VII. deposed from the clergy and from all ecclesiastical rank, clerics who took usury; and the same thing is the case with an infinite number of councils, in fact with nearly all e.g. Elvira, ij, Arles j, Carthage iij, Tours iij, etc. Nay, even the pagans themselves formerly forbid it by their laws." He then quotes Tacitus (Annal. lib. v.), and adds, "with what severe laws the French Kings coerced usurers is evident from the edicts of St. Louis, Philip IV., Charles IX., Henry III., etc."
There can be no doubt that Van Espen in the foregoing has accurately represented and without any exaggeration the universal opinion of all teachers of morals, theologians, doctors, Popes, and Councils of the Christian Church for the first fifteen hundred years. All interest exacted upon loans of money was looked upon as usury, and its reception was esteemed a form of theft and dishonesty. Those who wish to read the history of the matter in all its details are referred to Bossuet's work on the subject, Traité de l'Usure,  where they will find the old, traditional view of the Christian religion defended by one thoroughly acquainted with all that could be said on the other side.
The glory of inventing the new moral code on the subject, by which that which before was looked upon as mortal sin has been transfigured into innocence, if not virtue, belongs to John Calvin! He made the modern distinction between "interest" and "usury," and was the first to write in defence of this then new-fangled refinement of casuistry.  Luther violently opposed him, and Melancthon also kept to the old doctrine, though less violently (as was to be expected); today the whole Christian West, Protestant and Catholic alike, stake their salvation upon the truth of Calvin's distinction! Among Roman Catholics the new doctrine began to be defended about the beginning of the eighteenth century, the work of Scipio Maffei, Dell' impiego dell danaro, written on the laxer side, having attracted a widespread attention. The Ballerini affirm that the learned pope Benedict XIV. allowed books defending the new morals to be dedicated to him, and in 1830 the Congregation of the Holy Office with the approval of the reigning Pontiff, Pius VIII., decided that those who considered the taking of interest allowed by the state law justifiable, were "not to be disturbed." It is entirely disingenuous to attempt to reconcile the modern with the ancient doctrine; the Fathers expressly deny that the State has any power to make the receiving of interest just or to fix its rate, there is but one ground for those to take who accept the new teaching, viz. that all the ancients, while true on the moral principle that one must not defraud his neighbour nor take unjust advantage of his necessity, were in error concerning the facts, in that they supposed that money was barren, an opinion which the Schoolmen also held, following Aristotle. This we have found in modern times, and amid modern circumstances, to be an entire error, as Gury, the famous modern casuist, well says, "fructum producit et multiplicatur per se." 
That the student may have it in his power to read the Patristic view of the matter, I give a list of the passages most commonly cited, together with a review of the conciliar action, for all which I am indebted to a masterly article by Wharton B. Marriott in Smith and Cheetham's Dictionary of Christian Antiquities (s.v. Usury).
Although the conditions of the mercantile community in the East and the West differed materially in some respects, the fathers of the two churches are equally explicit and systematic in their condemnation of the practice of usury. Among those belonging to the Greek church we find Athanasius (Expos. in Ps. xiv); Basil the Great (Hom. in Ps. xiv). Gregory of Nazianzum (Orat. xiv. in Patrem tacentem). Gregory of Nyssa (Orat. cont. Usurarios); Cyril of Jerusalem (Catech. iv. c.37), Epiphanius (adv. Hæres. Epilog. c.24), Chrysostom (Hom. xli. in Genes), and Theodoret (Interpr. in Ps. xiv.5, and liv.11). Among those belonging to the Latin church, Hilary of Poitiers (in Ps. xiv); Ambrose (de Tobia liber unus). Jerome (in Ezech. vi.18); Augustine de Baptismo contr. Donatistas, iv.19); Leo the Great (Epist. iii.4), and Cassiodorus (in Ps. xiv.10).
The canons of later councils differ materially in relation to this subject, and indicate a distinct tendency to mitigate the rigour of the Nicæan interdict. That of the council of Carthage of the year 348 enforces the original prohibition, but without the penalty, and grounds the veto on both Old and New Testament authority, "nemo contra prophetas, nemo contra evangelia facit sine periculo" (Mansi, iii.158). The language, however, when compared with that of the council of Carthage of the year 419, serves to suggest that, in the interval, the lower clergy had occasionally been found having recourse to the forbidden practice, for the general terms of the earlier canon, "ut non liceat clericis fenerari," are enforced with greater particularity in the latter, "Nec omnino cuiquam clericorum liceat de qualibet re foenus accipere" (Mansi, iv.423). This supposition is supported by the language of the council of Orleans (a.d.538), which appears to imply that deacons were not prohibited from lending money at interest, "Et clericus a diaconatu, et supra, pecuniam non commodet ad usuras" (ib. ix.18). Similarly, at the second council of Trullanum (a.d.692) a like liberty would appear to have been recognised among the lower clergy (Hardouin, iii.1663). While, again, the Nicæan canon requires the immediate deposition of the ecclesiastic found guilty of the practice, the Apostolical canon enjoins that such deposition is to take place only after he has been admonished and has disregarded the admonition.
Generally speaking, the evidence points to the conclusion that the Church imposed no penalty on the layman. St. Basil (Epist. clxxxviii. can.12), says that a usurer may even be admitted to orders, provided he gives his acquired wealth to the poor and abstains for the future from the pursuit of gain (Migne, Patrol. Græc. xxxii.275). Gregory of Nyssa says that usury, unlike theft, the desecration of tombs, and sacrilege (hierosulia ), is allowed to pass unpunished, although among the things forbidden by Scripture, nor is a candidate at ordination ever asked whether or no he has been guilty of the practice (Migne, ib. xlv.233). A letter of Sidonius Apollinaris (Epist. vi.24) relating an experience of his friend Maximus, appears to imply that no blame attached to lending money at the legal rate of interest, and that even a bishop might be a creditor on those terms. We find also Desideratus, bishop of Verdun, when applying for a loan to king Theodebert, for the relief of his impoverished diocese, promising repayment, "cum usuris legitimis," an expression which would seem to imply that in the Gallican church usury was recognised as lawful under certain conditions (Greg. Tur. Hist. Franc. iii.34). So again a letter (Epist. ix.38) of Gregory the Great seems to shew that he did not regard the payment of interest for money advanced by one layman to another as unlawful. But on the other hand, we find in what is known as archbishop Theodore's "Penitential" (circ. a.d.690) what appears to be a general law on the subject, enjoining "Sie quis usuras undecunque exegerit...tres annos in pane et aqua" (c. xxv.3); a penance again enjoined in the Penitential of Egbert of York (c. ii.30). In like manner, the legates, George and Theophylact, in reporting their proceedings in England to pope Adrian I. (a.d.787), state that they have prohibited "usurers," and cite the authority of the Psalmist and St. Augustine (Haddan and Stubbs, Conc. iii.457). The councils of Mayence, Rheims, and Châlons, in the year 813, and that of Aix in the year 816, seem to have laid down the same prohibition as binding both on the clergy and the laity (Hardouin, Conc. iv.1011, 1020, 1033, 1100).
Muratori, in his dissertation on the subject (Antichità, vol. i.), observes that "we do not know exactly how commerce was transacted in the five preceding centuries," and consequently are ignorant as to the terms on which loans of money were effected.
 Van Espen, Dissertatio de Usura, Art. I.  Bossuet, OEuvres Comp. xxxj.  Funk (Zins und Wucher, p. 104) says that Eck and Hoogsträten had already verbally defended this distinction at Bologna.  Gury, Comp. Theol. Moral (Ed. Ballerini) vol. ii. p. 611.
 Bossuet, OEuvres Comp. xxxj.
 Funk (Zins und Wucher, p. 104) says that Eck and Hoogsträten had already verbally defended this distinction at Bologna.
 Gury, Comp. Theol. Moral (Ed. Ballerini) vol. ii. p. 611.