PREFACE 



the ablest of my pupils, Heinrich Schmidt, gave a sum- 

 mary and criticism of them in his Der Kampf urn die 

 Weltrdthsel, in the autumn of 1900. However, the 

 literary struggle went on to assume gigantic proportions 

 when twelve different translations of the Riddle appeared, 

 and led to an ever-increasing agitation in every educated 

 country of the Old and the New World. 



I gave a brief reply to the chief of these attacks in 

 April, 1903, in the appendix to the popular edition of the 

 Riddle. It would be useless to go further into this con- 

 troversy and meet the many attacks that have since been 

 made. It is a question here of that profound and irre- 

 concilable opposition between knowledge and faith, 

 between a real knowledge of nature and an alleged 

 "revelation," which has occupied the thoughtful and 

 inquiring mind for thousands of years. I base my 

 monistic philosophy exclusively on the convictions which 

 I have gained during fifty years' close and indefatigable 

 study of nature and its harmonious working. My dual- 

 istic opponents grant only a restricted value to these 

 experiences; they would subordinate them to the fan- 

 tastic ideas which they have reached by faith in a super- 

 natural world of spirits. An honest and impartial con- 

 sideration of this palpable contradiction discovers it to 

 be irreconcilable — either science and experience, or faith 

 and revelation! 



For this reason I do not propose to make any further 

 reply to the opponents of The Riddle of the Universe, and 

 I am still less disposed to take up the personal attacks 

 which some of my critics have thought fit to make on 

 me. In the course of this controversy I have grown 

 painfully familiar with the means with which it is sought 

 to silence the detested free-thinker — misrepresentation, 

 sophistry, calumny, and denunciation. ' ' Critical ' ' philos- 

 ophers of the modern Kantist school vie in this with 

 orthodox theologians. What I have said in this con- 



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