ide the question.
I do not maintain that birds are gifted with reasoning faculties at all
approaching in variety and extent to those of man. I simply hold that
the phenomena presented by their mode of building their nests, when
fairly compared with those exhibited by the great mass of mankind in
building their houses, indicate no essential difference in the kind or
nature of the mental faculties employed. If instinct means anything, it
means the capacity to perform some complex act without teaching or
experience. It implies innate ideas of a very definite kind, and, if
established, would overthrow Mr. Mill's sensationalism and all the
modern philosophy of experience. That the existence of true instinct may
be established in other cases is not impossible, but in the particular
instance of birds' nests, which is usually considered one of its
strongholds, I cannot find a particle of evidence to show the existence
of anything beyond those lower reasoning and imitative powers, which
animals are universally admitted to possess.

VII.

A THEORY OF BIRDS' NESTS;

SHOWING THE RELATION OF CERTAIN DIFFERENCES OF COLOUR IN FEMALE
BIRDS, TO THEIR MODE OF NIDIFICATION.

The habit of forming a more or less elaborate structure for the
reception of their eggs and young, must undoubtedly be looked upon as
one of the most remarkable and interesting characteristics of the class
of birds. In other classes of vertebrate animals, such structures are
few and exceptional, and never attain to the same degree of completeness
and beauty. Birds' nests have, accordingly, attracted much attention,
and have furnished one of the stock arguments to prove the existence of
a blind but unerring instinct in the lower animals. The very general
belief that every bird is enabled to build its nest, not by the ordinary
faculties of observation, memory, and imitation, but by means of some
innate and mysterious impulse, has had the bad effect of withdrawing
attention from the very evident relation that exists between the
structure, habits, and intelligence of birds, and the kind of nests they
construct.

In the preceding essay I have detailed several of these relations, and
they teach us, that a consideration of the structure, the food, and
other specialities of a bird's existence, will give a clue, and
sometimes a very complete one, to the reason why it builds its nest of
certain materials, in a definite situation, and in a more or less
elaborate m