receive a gain from his transactions, provided that they are not conducted with the sole object of making a profit, and that the gain he may receive must be limited by the common estimation of the place and time.  This is practically saying that cambium may be carried on under the same conditions as any other species of commerce.  Biel says that cambium is only legitimate if the campsor has the motive of keeping up a family or benefiting the State, and that the contract may become usurious if the gain is not fair and moderate.[3] The right of the campsor to some remuneration for risk was only gradually admitted, and forms the subject of much discussion amongst the jurists.[4] This hesitation in allowing remuneration for risk was not peculiar to cambium, but, as we have seen above, was common to all commerce.  Endemann points out how the theologians and jurists unanimously insisted that cambium could not be justified except when the just price was observed, and that, when the doctrine attained its full development, the element of labour was but one of the constituents in the estimation of that price.[5]

[Footnote 1:  ’Cum enim extraneae monetae communicantur in permutationibus oportet recurrere ad artem campsoriam, cum talia numismata non tantum valeant in regionibus extraneis quantum in propriis (De Reg.  Prin., ii. 13).]

[Footnote 2:  In Quot.  Lib.  Sent., iv. 16, 4.]

[Footnote 3:  Op. oil., IV. xv. 11.]

[Footnote 4:  Endemann, Studien, vol. i. pp. 123-36.]

[Footnote 5:  Ibid., p. 213.]

All the writers who treated of exchange divided it into three kinds; ordinary exchange of the moneys of different currencies (cambium minutum), exchange of moneys of different currencies between different places, the justification for which rested on remuneration for an imaginary transport (cambium per litteras), and usurious exchange of moneys of the same currency (cambium siccum).  The former two species of cambium were justifiable, whereas the last was condemned.[1]

[Footnote 1:  Laurentius de Rodulfis, De Usuris, pt. iii.  Nos. 1 to 5.]

The most complete treatise on the subject of money exchange is that of Thomas da Vio, written in 1499.  The author of this treatise divides money-changing into three kinds, just, unjust, and doubtful.  There were three kinds of just change; cambium minutum, in which the campsor was entitled to a reasonable remuneration for his labour; cambium per litteras, in which the campsor was held entitled to a wage (merces) for an imaginary transportation; and thirdly, when the campsor carried money from one place to another, where it was of higher value.  The unjust change was when the contract was a usurious transaction veiled in the guise of a genuine exchange.  Under the doubtful changes, the author discusses various special points which need not detain us here.