emned trade as being an
occupation fraught with danger to the soul. Tertullian argued that
there would be no need of trade if there were no desire for gain, and
that there would be no desire for gain if man were not avaricious.
Therefore avarice was the necessary basis of all trade.[1] St. Jerome
thought that one man's gain in trading must always be another's loss;
and that, in any event, trade was a dangerous occupation since it
offered so many temptations to fraud to the merchant.[2] St. Augustine
proclaimed all trade evil because it turns men's minds away from
seeking true rest, which is only to be found in God, and this opinion
was embodied in the _Corpus Juris Canonici_.[3] This early view that
all trade was to be indiscriminately condemned could not in the nature
of things survive experience, and a great step forward was taken
when Leo the Great pronounced that trade was neither good nor bad in
itself, but was rendered good or bad according as it was honestly or
dishonestly carried on.[4]

[Footnote 1: _De Idol_., xi.]

[Footnote 2: Ashley, _op. cit._, vol. i. pt. i. p. 129.]

[Footnote 3: See _Corpus Juris Canonici_, Deer. I.D. 88 c. 12.]

[Footnote 4: _Epist. ad Rusticum_, c. ix.]

The scholastics, in addition to condemning commerce on the authority
of the patristic texts, condemned it also on the Aristotelean ground
that it was a chrematistic art, and this consideration, as we have
seen above, enters into Aquinas's article on the subject.[1]

[Footnote 1: Rambaud, _op. cit._, p. 52.]

The extension of commercial life which took place about the beginning
of the thirteenth century, raised acute controversies about the
legitimacy of commerce. Probably nothing did more to broaden the
teaching on this subject than the necessity of justifying trade which
became more and more insistent after the Crusades.[1]

[Footnote 1: On the economic influence of the Crusades the following
works may be consulted: Blanqui, _Histoire de l'Economie politique_;
Heeren, _Essai sur l'Influence politique et sociale des Croisades_;
Scherer, _Histoire du Commerce_; Prutz, _Culturgeschichte der
Kreuzzuege_; Pigonneau, _Histoire du Commerce de la France_; List, _Die
Lehren der Handelspolitischen Geschichte_.]

By the time of Aquinas the necessity of commerce had come to be fully
realised, as appears from the passage in the _De Regimine Principum_:
'There are two ways in which it is possible to increase the affluence
of any State.