PREFACE 



the general problems of natural philosophy, especially 

 of biology, from a purely dualistic and teleological point 

 of view; these works were his Die Welt ah That (1899) 

 and Einleitung in die iheoretische Biologie (1902). As 

 both these works are well written and present the 

 principles of dualism and teleology with admirable con- 

 sistency — as far as this is possible — it seemed to me 

 that it was desirable to give a thorough exposition of my 

 own monistic and causative system. 



Hence the present work on the wonders of life is, as 

 the title indicates, a supplementary volume to The 

 Riddle of the Universe. While the latter undertook to 

 make a comprehensive survey of the general questions of 

 science — as cosmological problems — in the light of the 

 monistic philosophy, the present volume is confined to 

 the realm of organic science, or the science of life. It 

 seeks to deal connectedly with the general problems of 

 biology, in strict accord with the monistic and me- 

 chanical principles which I laid down in 1866 in my 

 General Morphology. In this I laid special stress on 

 the universality of the law of substance and the sub- 

 stantial unity of nature, which I have further treated 

 in the second and fourteenth chapters of The Riddle of 

 the Universe. 



The arrangement of the vast material for this study of 

 the wonders of life has been modelled on that of the 

 Riddle. I have retained the division into larger and 

 smaller sections and the synopses of the various chapters. 

 Thus the whole biological content falls into four sections 

 and twenty chapters. I should much have liked to add 

 illustrations in many parts of the text to make the sub- 

 ject plainer, especially as regards chapters vii., viii., 

 xi., and xvi. ; but this would have led to a considerable 

 increase in the size and price of the book. Moreover, 

 there are now many illustrated works which will help 

 the reader to go more fully into the various sections of 



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