because of the diversity of the currencies
in different kingdoms, and approves of the campsor receiving some
remuneration for his labour and trouble.[2] Nicholas de Ausmo, in
his commentary on the _Summa Pisana_, written in the beginning of the
fifteenth century, says that the campsor may 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 d