A TIIEOBY OF BIEDS' 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 a 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 



