A THEORY OF BIRDS’ NESTS. 235 
and accordingly the makers often put on a row of 
useless buttons or imitation laces, because habit ren- 
dered the appearance of them necessary to us. It is 
universally admitted that the habits of children and of 
savages give us the best clue to the habits and mode 
of thought of animals; and every one must have 
observed how children at first imitate the actions of 
their elders, without any regard to the use or appli- 
cability of the particular acts. So, in savages, many 
customs peculiar to each tribe are handed down from 
father to son merely by the force of habit, and are 
continued long after the purpose which they origi- 
nally served has ceased to exist. With these and a 
hundred similar facts everywhere around us, we may 
fairly impute much of what we cannot understand in 
the details of Bird-Architecture to an analogous cause. 
If we do not do so, we must assume, either that birds 
are guided in every action by pure reason to a far 
greater extent than men are, or that an infallible in- 
stinct leads them to the same result by a different 
road. The first theory has never, that I am aware 
of, been maintained by any author, and I have already 
shown that the second, although constantly assumed, 
has never been proved, and that a large body of facts. 
is entirely opposed to it. One of my critics has, in- 
deed, maintained that I admit “instinct” under the 
term “hereditary habit ;” but the whole course of my 
argument shows that I do not do so. Hereditary 
habit is, indeed, the same as instinct when the term 
is applied to some simple action dependent upon a 
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