8 PREFACE. 



until he had extracted its philosophical essence, and 

 in combining this essence with those of other sciences, 

 but not very apt in those further stages of analysis 

 which fall within the domain of philosophy itself. He 

 built wonderful edifices with the philosophic materials 

 that he found ready to hand, but he lacked the patience 

 and the minuteness of attention required for the crea- 

 tion of new materials. For this reason, his philosophy, 

 though brilliant, stimulating, and instructive, is not 

 among those that revolutionize fundamentals, or com- 

 pel us to remould our imaginative conception of the 

 nature of things. In fundamentals, broadly speaking, 

 he remained faithful to the authority of Kant. 



Readers of the following pages will not be surprised 

 to learn tliat his criticisms of mathematical logic do 

 not appear to me to be among the best parts of his 

 work. He was already an old man when he became 

 aware of the existence of this subject, and he was led, by 

 certain indiscreet advocates, to suppose it in some way 

 /opposed to those quick flashes of insight in mathe- 

 matical discovery which he has so admirably described- 

 No such opposition in fact exists ; but the misconcep- 

 tion, however regrettable, was in no way surprising. 



To be always right is not possible in philosophy ; 

 but Poincar^'s opinions, right or wrong, are always the 

 expression of a powerful and original mind with a 

 quite unrivalled scientific equipment ; a masterly style, 

 great wit, and a profound devotion to the advance- 

 ment of knowledge. Through these merits, his books 

 supply, better than any others known to me, the 

 growing need for a generally intelligible account of 

 the philosophic outcome of modern science. 



Bertrand Russell. 



