42 HUMAN AND BRUTE ACTION COMPARED. 
narrow extent of territory. Nature is allowed time and oppor- 
tunity to set her restorative powers at work, and the destructive 
animal has hardly retired from the field of his ravages before 
nature has repaired the damages occasioned by his operations. 
In fact, he is expelled from the scene by the very efforts which 
she makes for the restoration of her dominion. Man, on the 
contrary, extends his action over vast spaces, his revolutions are 
swift and radical, and his devastations are, for an almost ineal- 
culable time after he has withdrawn the arm that gave the blow, 
irreparable. 
The form of geographical surface, and very probably the 
climate of a given country, depend much on the character of 
the vegetable life belonging to it. Man has, by domestication, 
greatly changed the habits and properties of the plants he rears ; 
he has, by voluntary selection, immensely modified the forms 
and qualities of the animated creatures that serve him; and he 
has, at the same time, completely rooted out many forms of ani- 
mal if not of vegetable being.* What is there, in the 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, re- 
mained uninhabited by man or only thinly occupied by purely 
savage tribes, any sensible geographical change had occurred 
within twenty centuries before the epoch of discovery and colo- 
nization, while, during the same period, man had changed mil- 
* Whatever may be thought of the modification of organic species by natural 
selection, there is certainly no evidence that animals have exerted upon any 
form of life an influence analogous to that of domestication upon plants, quad- 
rupeds, 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, 
It is true that nature employs birds and quadrupeds for the dissemination 
of vegetable and even of animal species. But when the bird drops the seed 
of a fruit it has swallowed, and when the sheep transports in its fieece the 
seed-vessel of a burdock from the plain to the mountain, its action is purely 
mechanical and unconscious, and does not differ from that of the wind in pro- 
ducing the same effect. 
