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 des docteurs on peut trouver legitime la majoration du
prix. L'evaluation commune distingue un double element dans l'objet:
sa valeur ordinaire a laquelle repond le juste prix, et cette valeur
extraordinaire qui appartient au vendeur, dont il se prive et qui
merite une compensation: il le fait pour ainsi dire l'objet d'un
second contrat qui se superpose au premier. Cela est si vrai que le
supplement de prix n'est pas du au meme titre que le juste prix.'[2]
The importance of this analogy will appear when we come to treat just
price and usury in detail; it is simply referred to here in support of
the proposition that, far from being a special doctrine _sui generis_,
the usury doctrine of the Church was simply an application to the sale
of consumptible things of the universal rules which applied to all
sales. In other words, the doctrines of the just price and of usury
were founded on the same fundamental precept of justice in exchange.
If we indicate what this precept was, we can claim to have indicated
what was the true centre of the canonist doctrine.

[Footnote 1: _The Church and Usury_, p. 186.]

[Footnote 1: Desbuquois, 'La Justice dans l'Echange,' _Semaine Sociale
de France_, 1911, p. 174.]

The scholastic teaching on the subject of the rules of justice in
exchange was founded on the famous fifth book of Aristotle's _Ethics_,
and is very clearly set forth by Aquinas. In the article of the
_Summa_, where the question is discussed, 'Whether the mean is to be
observed in the same way in distributive as in commutative justice?'
we find a clear exposition: 'In commutations something is delivered to
an individual on account of something of his that has been received,
as may be seen chiefly in selling and buying, where the notion of
commutation is found primarily. Hence it is necessary to equalise
thing with thing, so that the one person should pay back to the other
just so much as he has become richer out of that w