PREFACE vii 



which is demanded at every step of what we term growth, 

 and often look upon as so simple and natural a process 

 as to require no explanation ; and, lastly, an ultimate 

 Purpose, in the very existence of the whole vast life-world 

 in all its long course of evolution throughout the eons of 

 geological time. This Purpose, which alone throws light on 

 many of the mysteries of its mode of evolution, I hold to be 

 the development of Man, the one crowning product of the 

 whole cosmic process of life-development ; the only being 

 which can to some extent comprehend nature ; which can 

 perceive and trace out her modes of action ; which can 

 appreciate the hidden forces and motions everywhere at 

 work, and can deduce from them a supreme and over- 

 ruling Mind as their necessary cause. 



For those who accept some such view as I have indicated, 

 I show (in Chapters XV. and XVI.) how strongly it is sup- 

 ported and enforced by a long series of facts and co-relations 

 which we can hardly look upon as all purely accidental 

 coincidences. Such are the infinitely varied products of 

 living things which serve man's purposes and man's alone — 

 not only by supplying his material wants, and by gratifying 

 his higher tastes and emotions, but as rendering possible 

 many of those advances in the arts and in science which we 

 claim to be the highest proofs of his superiority to the 

 brutes, as well as of his advancing civilisation. 



From a consideration of these better-known facts I 

 proceed (in Chapter XVII.) to an exposition of the mystery 

 of cell-growth ; to a consideration of the elements in their 

 special relation to the earth itself and to the life-world ; 

 while in the last chapter I endeavour to show the purpose 

 of that law of diversity which seems to pervade the whole 

 material Universe. As an " excursus," I devote Chapter XIX. 

 to a discussion of the nature, extent, and uses of Pain, as 

 strictly deduced from the law of Evolution. Strangely 

 enough, this has never, I believe, been done before ; and it 



