lo INTRODUCTION 



of Evolution are in the crucible of criticism, and 

 while the field of modern science changes with such 

 rapidity that in almost every department the text- 

 books of ten years ago are obsolete to-day, it is 

 fair to add that no one of these changes, nor all 

 of them together, have touched the general theory 

 itself except to establish its strength, its value, and 

 its universality. Even more remarkable than the 

 rapidity of its conquest is the authority with which 

 the doctrine of development has seemed to speak 

 to the most authoritative minds of our time. Of 

 those who are in the front rank, of those who by 

 their knowledge have, by common consent, the 

 right to speak, there are scarcely any who do not 

 in some form employ it in working and in think- 

 ing. Authority may mean little ; the world has 

 often been mistaken ; but when minds so different 

 as those of Charles Darwin and of T. H. Green, of 

 Herbert Spencer and of Robert Browning, build half 

 the labours of their life on this one law, it is im- 

 possible, and especially in the absence of any other 

 even competing principle at the present hour, to 

 treat it as a baseless dream. Only the peculiar 

 nature of this great generalization can account for 

 the extraordinary enthusiasm of this acceptance. 

 Evolution has done for Time what Astronomy has 

 done for Space. As sublime to the reason as the 



