SIR WILLIAM Hamilton's philosophy. 221 



ing. His explanation, as we have further seen, is that the belief in 

 the real existence of the objects of perception is only the belief that 

 they are really perceived, and that the belief in their existence be- 

 yond our minds, is simply the belief that they are perceived by an- 

 other mind, or by other minds : their existence, therefore, according 

 to him, consists in the perception of them by some mind ; and he is 

 consequently content to speak of them as ideas, which have no exis- 

 tence but in a mind. It is difficult to explain the shock which this 

 language created among Berkeley's antagonists, except by supposing 

 that they understood the preposition in as expressing some kind of 

 relation in place ; it is more difficult to conceive what mental fact 

 they understood it to denote, and most difficult of all to believe that 

 they had paid any attention to his own explanation, in accordance 

 with which to exist in a mind and to be known hy a mind are conver- 

 tible phrases * If this explanation had been noticed by Reid, it is 

 scarcely possible to believe that he could have placed himself in the 

 unmitigated antagonism, which he assumed, towards Berkeley ; for 

 the faith in a Primordial and Universal Mind involves the admission 

 that nothing exists which is not also known, or, in other words, that 

 everything exists in that Mind. Does the hostility between Berkeley 

 and Reid thus resolve itself wholly into a difference about the mean- 

 ing of words? There still remains one point at which the two doc- 

 trines seem to come into distinct collision ; for, while the Scottish 

 philosopher regards the material objects presented to the senses as 

 being the qualities of a substance which is not known by us,f but is, 

 of course, known by the Omniscient, the Irish philosopher protests 

 against the hypothesis of such an unknown substance, as not only 

 unnecessary to explain the phenomena of knowledge, but as contra- 

 dicting its essential conditions. 



I have already hinted the possibility of a doubt whether Reid has 

 hit upon the really fundamental principle of his philosophy, when he 

 elevates to that position his discovery, that the theory of perception 

 by means of ideas is without any ground in fact.. I believe the his* 

 torian of philosophy must decide that such a principle should be 

 recognised in Reid's antagonism, not to the " ideal theory," as he 

 calls it, but to the empirical theory regarding the origin of knowledge. 

 Whatever opinion may be formed of his opposition to the latter theory, 



* Works, Vol. I. p. 204. 



\ hitellectual Powers, Essay II., chap. 19. 



