SELECTION ON MAN, 5 315 
and finally become extinct. But man guards himself 
' from ‘such accidents by superintending and guiding 
the operations of nature. He plants the seed of his 
most agreeable food, and thus procures a supply, in- 
dependent of the accidents of varying seasons or na- 
tural extinction. He domesticates animals, which serve 
him either to capture food or for food itself, and thus, 
changes of any great extent in his teeth or digestive 
organs are rendered unnecessary. Man, too, has every- 
where the use of fire, and by its means can render 
palatable a variety of animal and vegetable substances, 
which he could hardly otherwise make use of; and thus 
obtains for himself a supply of food far more varied and 
abundant than that which any animal can command. 
Thus man, by. the mere capacity of clothing him- 
self, and making weapons dnd tools, has taken away 
from nature that power of slowly but permanently 
changing the external form and. structure, in accord- 
ance with changes in the external world, which she 
exercises over all other animals. As the competing 
races by which they are surrounded,. the climate, the 
vegetation, or the animals which serve them for food, 
are slowly changing, they must undergo a corre- 
sponding change in their structure, habits, and con- 
stitution, to keep them in harmony with the new 
conditions—to enable them to live and maintain their 
numbers. But man does this by means of his intellect 
alone, the variations of which enable him, with an 
unchanged body, still to keep in harmony with the 
changing universe. 
