XVI AUTHOR'S PREFACE. 



equal command of every branch of science, and largely 

 endowed with the artistic faculty of comprehensive 

 presentation, would be incapable of setting forth a 

 complete view of the cosmos in the space of a moderate 

 volume. My own command of the various branches 

 of science is uneven and defective, so that I can 

 attempt no more than to sketch the general plan of 

 such a world-picture, and point out the pervading 

 unity of its parts, however imperfect be the execution. 

 Thus it is that this work on the world-enigma has 

 something of the character of a sketch-book, in which 

 studies of unequal value are associated. As the 

 material of the book was partly written many 

 years ago, and partly produced for the first time 

 during the last few years, the composition is, unfor- 

 tunately, uneven at times ; repetitions, too, have proved 

 unavoidable. I trust those defects will be overlooked. 

 In taking leave of my readers, I venture the hope 

 that, through my sincere and conscientious work — in 

 spite of its faults, of which I am not unconscious — I 

 have contributed a little towards the solution of the 

 great enigma. Amid the clash of theories, I trust 

 that I have indicated to many a reader who is 

 absorbed in the zealous pursuit of purely rational 

 knowledge that path which, in my firm conviction, 

 alone leads to truth — the path of empirical investiga- 

 tion and of the Monistic Philosophy which is based 

 upon it. 



Ernst Haeckel. 



Jena, Germany, 1899. 



