no doubt that the doctrine of the canonists which impresses the modern mind most deeply is the usury prohibition, partly because it is not generally realised that the usury doctrine would not have forbidden the receipt of any of the commonest kinds of unearned revenue of the present day, and partly because the discussion of usury occupies such a very large part of the writings of the canonists.  It may be quite true to say that the doctrine of usury was that which gave the greatest trouble to the mediaeval writers, on account of the nicety of the distinctions with which it abounded, and on account of the ingenuity of avaricious merchants, who continually sought to evade the usury laws by disguising illegal under the guise of legal transactions.  In practice, therefore, the usury doctrine was undoubtedly the most prominent part of the canonist teaching, because it was the part which most tempted evasion; but to admit that is not to agree with the proposition that it was the centre of the canonist doctrine.

[Footnote:  1 Op. cit., vol. i. pt. ii. p. 399.]

[Footnote:  2 ’Bekanntlich war das Wucherverbot der praktische Mittelpunkt der ganzen kanonischen Wirthschaftspolitik,’ Op. cit., p. 8.]

[Footnote:  3 Studien, vol. i. p. 2 and passim.  At vol. ii. p. 31 it is stated that the teaching on just price is a corollary of the usury teaching.  But Aquinas treats of usury in the article following his treatment of just price.]

Our view is that the teaching on usury was simply one of the applications of the doctrine that all voluntary exchanges of property must be regulated by the precepts of commutative justice.  In one sense it might be said to be a corollary of the doctrine of just price.  This is apparently the suggestion of Dr. Cleary in his excellent book on usury:  ’It seems to me that the so-called loan of money is really a sale, and that a loan of meal, wine, oil, gunpowder, and similar commodities—­that is to say, commodities which are consumed in use—­is also a sale.  If this is so, as I believe it is, then loans of all these consumptible goods should be regulated by the principles which regulate sale contracts.  A just price only may be taken, and the return must be truly equivalent.’[1] This statement of Dr. Cleary’s seems well warranted, and finds support in the analogy which was drawn between the legitimacy of interest—­in the technical sense—­and the legitimacy of a vendor’s increasing the price of an article by reason of some special inconvenience which he would suffer by parting with it.  Both these titles were justified on the same ground, namely, that they were in the nature of compensations, and arose independently of the main contract of loan or sale as the case might be.  ’Le vendeur est en presence de l’acheteur.  L’objet a pour lui une valeur particuliere:  c’est un souvenir, par exemple.  A-t-il le droit de majorer le prix de vente? de depasser le juste prix convenu? ...  Avec l’unanimite