262 A THEORY OF BIRDS’ NESTS. 
too often looked upon as something adventitious and 
superficial, something 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 organised beings would 
be an exception to most other natural phenomena. 
They would not be the product of general laws, or 
determined by ever-changing external conditions ; 
and we must give up all enquiry into their’ origin 
and causes, since’ (by the hypothesis) they are de- 
pendent on a Will whose motives must ever be un- 
known 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 attempted to elucidate some of these laws 
in the case of birds, and have shown how the mode 
of nidification has affected the colouring of the female 
sex in thisgroup. I have before shown to how great 
an extent, and in how many ways, the need of pro- 
tection has determined the colours of insects, and of 
some groups of reptiles and mammalia, and I would 
now call particular attention to the fact that the gay 
tints of flowers, so long supposed to be a convincing 
proof that colour has been bestowed for other pur- 
poses than the good of its possessor, have been shown 
by Mr. Darwin to follow the same great law of utility. 
Flowers do not often need protection, but very often 
