vi A PREFATORY LETTER. 



concluding which it is necessary for me to notify you, and any 

 other reader, of two or three matters. 



The first is, that the oldest Essay of the whole, that &quot; On 

 the Educational Value of the Natural History Sciences,&quot; 

 contains a view of the nature of the differences between 

 living and not-living bodies out of which I have long since 

 grown. 



Secondly, in the same paper, there is a statement concerning 

 the method of the mathematical sciences, which, repeated and 

 expanded elsewhere, brought upon me, during the meeting of 

 the British Association at Exeter, the artillery of our eminent 

 friend, Professor Sylvester. 



No one knows better than you do, how readily I should defer 

 to the opinion of so great a mathematician if the question at 

 issue were really, as he seems to think it is, a mathematical 

 one. But I submit that the dictum of a mathematical athlete 

 upon a difficult problem which mathematics offers to philosophy, 

 has no more special weight, than the verdict of that great 

 pedestrian Captain Barclay would have had, in settling a 

 disputed point in the physiology of locomotion. 



The genius which sighs for new worlds to conquer beyond 

 that surprising region in which &quot;geometry, algebra, and the 

 theory of numbers melt into one another like sunset tints, or 

 the colours of a dying dolphin,&quot; may be of comparatively little 

 service in the cold domain (mostly lighted by the moon, some 

 say) of philosophy. And the more I think of it, the more 

 does our friend seem to me to fall into the position of one of 



