commerce was not altogether to be condemned, and might even be laudable,
provided the merchant retired early from trade and invested his gaits in
farm lands.--De Officiis, lib. i.,42.] Hence, large tracts of land were
left uncultivated, or altogether deserted, and exposed to all the
destructive forces which act with such energy on the surface of the
earth when it is deprived of those protections by which nature
originally guarded it, and for which, in well-ordered husbandry, human
ingenuity has contrived more or less efficient substitutes. [Footnote:
The temporary depopulation of an exhausted soil may be, in some cases, a
physical, though, like fallows in agriculture, a dear-bought advantage.
Under favorable circumstances, the withdrawal of man and his flocks
allows the earth to clothe itself again with forests, and in a few
generations to recover its ancient productiveness. In the Middle Ages,
worn-out fields were depopulated, in many parts of the Continent, by
civil and ecclesiastical tyrannies, which insisted on the surrender of
the half of a loaf already too small to sustain its producer. Thus
abandoned, these lands often relapsed into the forest state, and, some
centuries later, were again brought under cultivation with renovated
fertility.] Similar abuses have tended to perpetuate and extend these
evils in later ages, and it is but recently that, even in the most
populous parts of Europe, public attention has been half awakened to the
necessity of restoring the disturbed harmonies of nature, whose
well-balanced influences are so propitious to all her organic offspring,
and of repaying to our great mother the debt which the prodigality and
the thriftlessness of former generations have imposed upon their
successors--thus fulfilling the command of religion and of practical
wisdom, to use this world as not abusing it.


Reaction of Man on Nature.