AUTHOR'S PREFACE. Xlll 



which we briefly denominate the " world-riddles." 

 The studies of these " world-riddles " which I offer 

 in the present work cannot reasonably claim to give a 

 perfect solution of them : they merely offer to a wide 

 circle of readers a critical inquiry into the problem, 

 and seek to answer the question as to how nearly we 

 have approached that solution at the present day. 

 What stage in the attainment of truth have we 

 actually arrived at in this closing year of the 

 nineteenth century? What progress have we really 

 made during its course towards that immeasurably 

 distant goal ? 



The answer which I give to these great questions 

 must, naturally, be merely subjective and only partly 

 correct ; for my knowledge of nature and my ability 

 to interpret its objective reality are limited, as are 

 those of every man. The one point that I can claim, 

 and which, indeed, I must ask of my strongest 

 opponents, is that my Monistic Philosophy is sincere 

 from beginning to end — it is the complete expression 

 of the conviction that has come to me, after many 

 years of ardent research into Nature and unceasing 

 reflection, as to the true basis of its phenomena. 

 For fully half a century has my mind's work pro- 

 ceeded, and I now, in my sixty- sixth year, may 

 venture to claim that it is mature ; I am fully 

 convinced that this " ripe fruit " of the tree of know- 

 ledge will receive no important addition and suffer no 

 substantial modification during the brief spell of life 

 that remains to me. 



