PHYSICAL DECAY. 
43 
tlie influence of brute life, that corresponds to this ? We have 
no reason to believe that in that portion of the American 
continent which, though peopled by many tribes of quadruped 
and fowl, remained uninhabited by man, or only thinly occu¬ 
pied by purely savage tribes, any sensible geographical change 
had occurred within twenty centuries before the epoch of 
discovery and colonization, while, during the same period, 
man had changed millions of square miles, in the fairest and 
most fertile regions of the Old World, into the barrenest 
deserts. 
The ravages committed by man subvert the relations and 
destroy the balance which nature had established between her 
organized and her inorganic creations; and she avenges her¬ 
self upon the intruder, by letting loose upon her defaced 
provinces destructive energies hitherto kept in check by 
organic forces destined to be his best auxiliaries, but which he 
has unwisely dispersed and driven from the field of action. 
When the forest is gone, the great reservoir of moisture stored 
up in its vegetable mould is evaporated, and returns only in 
deluges of rain to wash away the parched dust into which that 
mould has been converted. The well-wooded and humid hills 
are turned to ridges of dry rock, which encumbers the low 
grounds and chokes the watercourses with its debris, and— 
except in countries favored with an equable distribution of 
rain through the seasons, and a moderate and regular inclina¬ 
tion of surface—the whole earth, unless rescued by human art 
from the physical degradation to which it tends, becomes an 
assemblage of bald mountains, of barren, turfless hills, and of 
swampy and malarious plains. There are parts of Asia Minor, 
of Northern Africa, of Greece, and even of Alpine Europe, 
where the operation of causes set in action by man has 
brought the face of the earth to a desolation almost as com- 
plete as that of the moon ; and though, within that brief space 
upon any form of life an influence analogous to that of domestication upon 
plants, quadrupeds, and birds reared artificially by man; and this is as 
true of unforeseen as of purposely effected improvements accomplished by 
voluntary selection of breeding animals. 
