PREFACE xui 



book now seems like a small memorial to them, which they 

 would not despise. It is also time for such a memorial. For 

 the number of those who are able to think in the manner of 

 these investigators appears to be very much on the decline 

 at the present time; and yet no other manner of thought has 

 proved capable of more than mere momentary success, or the 

 production of astonishment, or in the best case, as the con- 

 clusion of what has already been properly founded. Indeed, 

 the point of view of these investigators is alone capable of 

 leading to the solution of the questions of the moral sciences; 

 for these questions also relate to natural processes, and 

 nature is a unity. 



This attitude of mind must therefore not be forgotten; it 

 must again be cultivated and made to live, and no better 

 means to this end can be found than a care for the memory of 

 these great scientists. It cannot be hidden from anyone 

 who looks well below the surface, that none of the achieve- 

 ments of the human mind are more firmly founded, none are 

 of more permanent value, than the achievements of these 

 men. The last fifteen years have led all those who have 

 devoted serious thought to what has been happening, to 

 realise that much that was earlier accepted and regarded as 

 assured, is doubtful, nay erroneous, when seen in the light 

 of to-day. Our view of the world has changed, and new 

 knowledge has come to us. But these men and their con- 

 tributions to our world-view have remained what they were 

 already; indeed, the reputation and importance of them must 

 even appear increased, inasmuch as we now see very clearly 

 how very much further removed they were from error - 

 and the greatest pioneers among them most of all - than 

 their contemporaries. 



The new knowledge has also put the kinship of the great 

 investigators, which I am concerned to demonstrate in the 

 present book from the manner of their thought, their striving, 

 and their work, and also their whole spiritual nature, in a new 



