X PREFACE TO THE SECOND EDITION 



and consolidate the questions which beset him 

 in his journeyings through time and space. To 

 the philosophic import of this mental attitude 

 Mr Balfour has done well to call attention in 

 words that he kindly allows the writer to re- 

 produce : — 



'' Now whether the main outlines of the world- 

 picture which I have just imperfectly presented 

 to you be destined to survive, or whether in 

 their turn they are to be obliterated by some 

 new drawing on the scientific palimpsest, all 

 will, I think, admit that so bold an attempt to 

 unify physical nature excites feelings of the most 

 acute intellectual gratification. The satisfaction 

 it gives is almost aesthetic in its intensity and 

 quality. We feel the same sort of pleasurable 

 shock as when from the crest of some melancholy 

 pass we first see far below us the sudden glories 

 of plain, river, and mountain. Whether this 

 vehement sentiment in favour of a simple universe 

 has any theoretical justification, I will not venture 

 to pronounce. There is no a priori reason that 

 I know of for expecting that the material world 

 should be a modification of a single medium, 

 rather than a composite structure built out of 

 sixty or seventy elementary substances, eternal 

 and eternally different. Why, then, should we 

 feel content with the first hypothesis and not 

 with the second ? Yet so it is. Men of science 

 have always been restive under the multiplication 

 of entities. They have eagerly noted any sign 

 that the chemical atom was composite, and that 

 the different chemical elements had a common 

 origin. Nor for my part do I think such instincts 

 should be ignored. . . . These obscure intima- 



