170 
INSTINCTS. 
transition from summer to winter carries us into the very 
midst of physical astronomy; that is to say, into the midst 
of those laws which govern the solar system at least, and 
probably all the heavenly bodies. 
CHAPTER XVIII. 
INSTINCTS. 
The order may not be very obvious, by which I place 
instincts next to relations. But I consider them as a 
species of relation. They contribute, along with the ani¬ 
mal organization, to a joint effect, in which view they are 
related to that organization. In many cases, they refer 
from one animal to another animal; and when this is the 
case, become strictly relations in a second point of view. 
An instinct is a propensity prior to experience, and 
independent of instruction. We contend, that it is by 
instinct that the sexes of animals seek each other; that 
animals cherish their offspring; that the young quadruped 
is directed to the teat of its dam; that birds build their 
nests, and brood with so much patience upon their eggs; 
that insects which do not sit upon their eggs, deposit them 
in those particular situations, in which the young, when 
hatched, find their appropriate food; that it is instinct 
which carries the salmon, and some other fish, out of the 
sea into rivers, for the purpose of shedding their spawn in 
fresh water. 
We may select out of this catalogue the incubation of 
eggs. I entertain no doubt, but that a couple of sparrows 
hatched in an oven, and kept separate from the rest of 
their species, would proceed as other sparrows do, in every 
office which related to the production and preservation of 
their brood. Assuming this fact, the thing is inexplicable 
upon any other hypothesis than that of an instinct impress¬ 
ed upon the constitution of the animal. For, first, what 
should induce the female bird to prepare a nest before she 
lays her eggs? It is in vain to suppose her to be possess¬ 
ed of the faculty of reasoning; for no reasoning will reach 
the case. The fulness or distention which she might feel 
in a particular part of her body, from the growth and so¬ 
lidity of the egg within her, could not possibly inform her, 
that she was about to produce something, which, when pro- 
