wi A PREFATORY LETTER. 



The first is, that the oldest Essay of the whole, that 

 "On the Educational Value of the Natural History 

 Sciences/' 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 con- 

 cerning; 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 "geometry, 

 algebra, and the theory of numbers melt into one another 

 like sunset tints, or the colours of a dying dolphin," 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 those 

 "verstitndige Leute," about whom he makes so apt a 

 quotation from Goethe. Surely he has not duly con- 

 sidered two points. The first, that I am in no way 



