14 
INFLUENCE OF HUMAN ACTION. 
to say liow far they have been compensated by each other, or 
by still obscurer influences; and, Anally, that the myriad 
forms of animal and vegetable life, which covered the earth 
when man first entered upon the theatre ot a nature whose 
harmonies he was destined to derange, have been, through his 
action, greatly changed in numerical proportion, sometimes 
much modified in form and product, and sometimes entirely 
extirpated. 
The physical revolutions thus wrought by man have not 
all been destructive to human interests. Soils to which no 
nutritious vegetable was indigenous, countries which once 
brought forth but the fewest products suited for the sustenance 
and comfort of man—while the severity of their climates cre¬ 
ated and stimulated the greatest number and the most impe¬ 
rious urgency of physical wants—surfaces the most rugged 
and intractable, and least blessed with natural facilities of com¬ 
munication, have been made in modern times to yield and 
distribute all that supplies the material necessities, all that 
contributes to the sensuous enjoyments and conveniences of 
civilized life. The Scythia, the Thule, the Britain, the Ger¬ 
many, and the Gaul which the Roman writers describe in such 
forbidding terms, have been brought almost to rival the native 
luxuriance and easily won plenty of Southern Italy; and, 
while the fountains of oil and wine that refreshed old Greece 
and Syria and Northern Africa have almost ceased to flow, 
and the soils of those fair lands are turned to thirsty and inhos¬ 
pitable deserts, the hyperborean regions of Europe have con¬ 
quered, or rather compensated, the rigors of climate, and 
attained to a material wealth and variety of product that, 
with all their natural advantages, the granaries of the ancient 
world can hardly be said to have enjoyed. 
These changes for evil and for good have not been caused 
by great natural revolutions of the globe, nor are they by any 
means attributable wholly to the moral and physical action or 
inaction of the peoples, or, in all cases, even of the races that 
now inhabit these respective regions. They are products of a 
complication of conflicting or coincident forces, acting through 
