172 
INSTINCTS. 
But admit the sparrow by some means to know, that 
within that egg was concealed the principle of a future 
bird, from what chemist was she to learn, that warfnth was 
necessary to bring it to maturity, or that the degree of 
warmth, imparted by the temperature of her own body, was 
the degree required? 
To suppose, therefore, that the female bird acts in this 
process from a sagacity and reason of her own, is to sup¬ 
pose her to arrive at conclusions which there are no prem¬ 
ises to justify. If our sparrow, sitting upon her eggs, 
expect young sparrows to come out of them, she forms, I 
will venture to say, a wild and extravagant expectation, in 
opposition to present appearances, and to probability. She 
must have penetrated into the order of nature, farther than 
any faculties of ours will carry us; and it hath been well ob¬ 
served, that this deep sagacity, if it be sagacity, subsists in 
conjunction with great stupidity, even in relation to the same 
subject. “ A chemical operation, ” saysAddison, “could not 
be followed with greater art or diligence, than is seen in 
hatching a chicken; yet is the process carried on without 
the least glimmering of thought or common sense. The 
hen will mistake a piece of chalk for an egg; is insensible 
of the increase or diminution of their number; does not dis¬ 
tinguish between her own and those of another species; is 
frightened when her supposititious breed of ducklings take 
the water.” 
But it will be said, that what reason could not do for 
the bird, observation, or instruction, or tradition, might. 
Now, if it be true, that a couple of sparrows, brought up 
from the first in a state of separation from all other birds, 
would build their nest, and brood upon their eggs, then 
there is an end of this solution. What can be the tradi¬ 
tionary knowledge of a chicken hatched in an oven? 
Of young birds taken in their n^sts, a few species breed 
when kept in cages; and they which do so, build their 
nests nearly in the same manner as in the wild state, and 
sit upon their eggs. This is sufficient to prove an instinct, 
without having recourse to experiments upon birds hatched 
by artificial heat, and deprived from their birth of all 
communication with their species; for we can hardly bring 
ourselves to believe, that the parent bird informed her un¬ 
fledged pupil of the history of her gestation, her timely 
preparation of a nest, her exclusion of the eggs, her long 
incubation, and of the joyful eruption at last of her expected 
offspring; all which the bird in the cage must have learned 
in her infancy, if we resolve her conduct into institution 
