380 Darwin, and after Darwin. 
It is a matter of observation that the higher 
animals do not pair indiscriminately ; but that the 
members of either sex prefer those individuals of the 
opposite sex which are to them most attractive. It 
is important to understand iz /imine that nobody has 
ever attempted to challenge this statement. In other 
words, it is an unquestionable fact that among many of 
the higher animals there literally and habitually occurs 
a sexual selection; and this fact is not a matter of 
‘inference, but, as I have said, a matter of observation. 
The inference only begins where, from this observable 
fact, it is argued,—1st, that the sexual selection has 
reference to an esthetic taste on the part of the 
animals themselves; and 2nd, that, supposing the 
selection to be determined by such a taste, the cause 
thus given .is adequate to explain the phenomena of 
beauty which are presented by these animals. I will 
consider these two points separately. 
From the evidence which Darwin has collected, it 
appears to me impossible to doubt that an esthetic 
sense is displayed by many birds, and not a few 
mammals. This of course does not necessarily imply 
that the standards of such a sense are the same as 
our own; nor does it necessarily imply that there is 
any constant relation between such a sense and high 
levels of intelligence in other respects. In point of 
fact, such is certainly not the case, because the best 
evidence that we have of an zsthetic sense in animals 
is derived from birds, and not from mammals. The 
most cogent cases to quote in this connexion are 
those of the numerous species of birds which habi- 
tually adorn their nests with gaily coloured feathers, 
wool, cotton, or any other gaudy materials which they 
