The Theory of Sexual Selection. 407 



form most effectual for spreading out the leaves to the 

 light and air. Here, then, we likewise find that the 

 cause determining plant beauty is natural selection ; 

 and so we may conclude that the only reason why 

 the forms of trees which are thus determined by 

 utility appeal to us as beautiful, is because we are 

 accustomed to these the most ordinary forms. Our 

 ideas having been always, as it were, moulded upon 

 these forms, aesthetic feeling becomes attached to 

 them by the principle of association. At any rate, it 

 is certain that when we contemplate almost any forms 

 of plant-structure which, for special reasons of utility, 

 differ widely from these (to us) more habitual forms, 

 the result is not sugi^estive of beauty. Many of the 

 tropical and un-tree-like plants — such as the cactus 

 tribe — strike us as odd and quaint, not as beautiful. 

 Be this however as it may, I trust I have said enough 

 to prove that in the vegetable world, at all events, the 

 attainment of beauty cannot be held to have been an 

 object aimed at, so to speak, for its own sake. Even 

 if, for the purposes of argument, we were to suppose 

 that all the forms and colours in the vegetable world 

 are due to special design, there could be no doubt 

 that the purpose of this design has been in chief part 

 a utilitarian purpose ; it has not aimed at beauty ex- 

 clusively for its own sake. For most of such beauty as 

 we here perceive is plainly due to the means adopted 

 for the attainment of life-preserving ends, which, of 

 course, is a me-taphorical way of saying that it is 

 probably due to natural selection ^. 



' The beauty of autumnal tints in fading leaves may possibly be 

 adduced per contra. But here we have to remember that it is only 

 some kinds of leaves which thus become beautiful when fading, while, 



