A THEOEY OF ZIBDS' XESTS. 201 



Darwin informs me he has facts to support), I impute 

 the difference, in the great majority of cases, to the 

 greater or less need of protection in the female sex in 

 these groups of animals. 



Conclusion. 



To some persons it will perhaps appear, that the 

 causes to which I impute so much of the external as- 

 pect of nature are too simple, too insignificant, and too 

 unimportant for such a mighty work. But I would 

 ask them to consider, that the great object of all the 

 peculiarities of animal structure is to preserve the life 

 of the individual, and maintain the existence of the 

 species. Colour has hitherto been too often looked 

 upon as something adventitious and superficial, some- 

 thing given to an animal not to be useful to itself, but 

 solely to gratify man or even superior beings to add 

 to the beauty and ideal harmony of nature. If this 

 were the case, then, it is evident that the colours of 

 organized beings would be an exception to most other 

 natural phenomena. They would not be the product 

 of general laws, or determined by ever-changing ex- 

 ternal conditions ; and we must give up all inquiry 

 into their origin and causes, since (by the hypothesis) 

 they are dependent on a Will whose motives must ever 

 be unknown to us. But, strange to say, no sooner do 

 we begin to examine and classify the colours of natural 

 objects, than we find that they are intimately related 

 to a variety of other phenomena, and are like them 

 strictly subordinated to general laws. I have here 



