X PREFACE 



of the globe has ever proceeded from the uniform to the complex ; 

 and in the closing chapter of this book an endeavour is made to 

 connect the differentiation of plant and bird with the differentiation 

 of the conditions of existence on the earth. But this leaves no 

 room for the development of new types of organisms ; and so far 

 as observation of the processes of Nature at present working around 

 us can guide us, each type might well be regarded as eternal. We 

 can never hope to arrive at an explanation of the progressive 

 development of types by studying the differentiating process ; 

 and since the last is alone cognisable for us, evolution, as it is 

 usually termed, becomes an article of our faith, and of faith only. 



In illustration of this argument, let me take the case of the 

 races of men. We see mankind in our own day illustrating the 

 law of differentiation all over the globe, as far as physical charac- 

 ters are concerned. Just as the ornithologist would postulate a 

 generalised type in tracing the origin of various allied groups of 

 birds, so the anthropologist, guided by his observation of the 

 changes now offered by man in different regions, would postulate 

 a generalised original type as the parent-stock of mankind. 

 Observation of the processes of change now in operation by no 

 means leads us to infer that such a generalised type was an 

 anthropoid ape, or even simian in character. In so doing we 

 should be forming a conclusion not warranted by the observation 

 of existing agencies of change, and we should be confusing the 

 two distinct processes of evolution and differentiation, or rather 

 of progressive and divergent evolution, of which the last alone 

 comes within our field of cognition. The study of variation can 

 do no more than enable us to ascertain the mode of development 

 of different kinds, we will say, of birds or of men. The origin of 

 the type lies outside our observation. " Given the type, to explain 

 its origin " : this is the problem we can never solve, and Nature 

 aids us nothing by the study of her ways. On the other hand, 

 there is the subsidiary problem ..." Given a type, to explain its 

 varieties " . . . ; and here Nature's processes are apparent to us in 

 a thousand different shapes. 



It might seem that the presumptive evidence connecting man 

 in his origin with the monkeys is so strong that, supposing his 



