tion (1)
the prevalent influence of religious ideas at the time, (2) the
strong reaction against the materialism of pagan antiquity, (3)
the predominance of natural economy, (4) the small importance of
international trade, and (5) the decay of the profane sciences, and
the metaphysical tendencies of the more solid thinkers of the Middle
Ages.'[1]

[Footnote 1: _Op. cit._, p. 14; Espinas, _op. cit._, p. 80.]

The teaching of Aquinas upon economic affairs remained the groundwork
of all the later writers until the end of the fifteenth century.
His opinions on various points were amplified and explained by
later authors in more detail than he himself employed; monographs of
considerable length were devoted to the treatment of questions which
he dismissed in a single article; but the development which took
place was essentially one of amplification rather than opposition. The
monographists of the later fifteenth century treat usury and sale in
considerable detail; many refinements are indicated which are not
to be found in the _Summa_; but it is quite safe to say that none
of these later writers ever pretended to supersede the teaching of
Aquinas, who was always admitted to be the ultimate authority. 'During
the fourteenth and fifteenth centuries, the general political doctrine
of Aquinas was maintained with merely subordinate modifications.'[1]
'The canonist doctrine of the fifteenth century,' according to Sir
William Ashley, 'was but a development of the principles to which the
Church had already given its sanction in earlier centuries. It was the
outcome of these same principles working in a modified environment.
But it may more fairly be said to present a _system_ of economic
thought, because it was no longer a collection of unrelated opinions,
but a connected whole. The tendency towards a separate department of
study is shown by the ever-increasing space devoted to the discussion
of general economic topics in general theological treatises, and
more notably still in the manuals of casuistry for the use of the
confessional, and handbooks of canon law for the use of ecclesiastical
lawyers. It was shown even more distinctly by the appearance of a
shoal of special treatises on such subjects as contracts, exchange,
and money, not to mention those on usury.'[2] In all this development,
however, the principles enunciated by Aquinas, and through him, by
Aristotle, though they may have been illustrated and applied to new
insta