xxxii PREFACE TO THE THIRD EDITION. 



task of accumulating dry details to wider views, and thus to 

 gain sympathy with aUied aims. On the other side, the 

 sterility of such pure speculative philosophy as ignores all 

 those enormous advances in empiric knowledge, has so 

 forced its way into the consciousness of all sound thinkers, 

 that they earnestly desire to fall back on the firm basis 

 afforded by experimental science. 



The ever-increasing flood of writings on natural philo- 

 sophy, and essays on the relation of philosophy to natural 

 science, plainly indicates the happy growth of this scientific 

 unitary tendency. Nothing is more favourable to this, 

 nothing better advances the combination of the various 

 scientific lines, than the new theory of evolution. The 

 extraordinary importance ascribed to this theory, rests 

 especially on the fact that it supplies a philosophic central 

 point, and just for this very reason it has in so short a 

 time gained the active interest of all thoughtful minds. 

 It raises us from a knowledge of facts to a knowledge of 

 causes, and thus affords a deeper satisfaction to the 

 demand for causality innate in human reason than a mere 

 experimental science could ever supply. When, therefore, 

 Karl Vogt and many other naturalists entirely reject philo- 

 sophy, and will not allow that it has any point of union 

 with what is called " exact " natural science they volun- 

 tarily renounce all the higher aims of investigation. 

 (Cf. vol. ii. p. 387.) 



Albert Kolliker occupies a similarly one-sided stand- 

 point. This author, in the second edition of his " History 

 of the Evolution of Man and the Higher Animals " (" Ent- 

 wickelungsgeschichte des Menschen und der Hoheren 

 Thiere," 1876), nr-especially attacking the fundamental laiv 



