50 THOUGHTS UPON THE MUSICAL SENSE [X. 



Sexual selection, as we may suppose, has made this language 

 an essential part of its being. 



It is otherwise with man : his language does not exist as a 

 perfected faculty, as a part of his physical nature ; but only as a 

 possible expression of it which only becomes actual when the 

 individual preserves communication with those who preceded 

 him, viz. when he is taught to speak. Hence it is that every 

 human child can learn any language : hence it is that there is 

 not one single human language but hundreds of them, each of 

 which has had its own developmental history— its origin, 

 climax, and dechne. Each of these different modes of expres- 

 sion of the human mind seems, as it were, a distinct mental 

 entity, independent of the individual, and possessing its own 

 history. And this is not only true of language, but also of the arts 

 and sciences. Not one of these could have existed had not man 

 possessed that advantage over animals which enables him to 

 transmit the knowledge he has gained to his descendants, so 

 that these latter are benefited by building, from the very first, 

 upon the high level reached by previous generations, from 

 which they can rise still higher. 



All this is far from new : it has long been known that the 

 chief difference between man and animals consists in the fact 

 that man is capable of mental development while animals are 

 not. But I doubt whether the exact difference has ever been 

 clearly conceived. The statement just made is not a satis- 

 factory expression of it ; for common knowledge of the day 

 asserts that animals are certainly capable of development 

 although in a sense entirely different from that which is 

 intended above. We have every reason for the behef that the 

 unceasing transformation of species which took place during 

 the earlier epochs of the world's history, is also proceeding to- 

 day—that to-day, wherever circumstances are favourable, the 

 transformation of species is taking place, although slowly and 

 insensibly. But such a process of development of one species 

 of animal into a new one, even when combined with an 

 improvement and increase in efficiency, is entirely different 

 from what we mean by the development of mankind. 



The development of animals transforms one species into 

 another and changes the physical nature : but what we 

 generally understand by the intellectual development of man- 



