Philosophy of the Human Mind. 5 



of ideas, concerning the use and abuse of terms, 

 and concerning the extent and limits of our intel- 

 lectual powers, are well known by those conver- 

 sant with the philosophy of mind, to display many 

 new doctrines, and to place their author among 

 the most profound thinkers. Mr. Locke differed 

 from Des Cartes with respect to the origin of our 

 ideas. The latter thought some of them were in- 

 nate ; the former maintained that there are no in- 

 nate ideas, and that they are all derived from two 

 sources, sensation and reflection. Des Cartes sup- 

 posed that the essence of mind consists in thought, 

 and that of matter in extension ; while Locke be- 

 lieved that the real essence of both is beyond the 

 reach of human knowledge. The British philoso- 

 pher explained more distinctly than any one had 

 done before him, the operations of the mind in 

 clasping the various objects of thought, and re- 

 ducing them to genera and species. He was the 

 first who distinguished in substances what he calls 

 the nominal essence, or that generic character, and 

 specific difference, which may be expressed by a 

 definition, from the real essence, or internal con- 

 stitution, which he supposed could not be known; 

 and who, by means of this distinction, pointed out 

 the way of bringing to an issue those subtle dis- 

 putes, particularly the controversy between the 

 Nominalists and Realists, which had puzzled the 

 schoolmen for ages. He showed, more satisfacto- 

 rily than preceding inquirers, how we form abstract 

 and general notions, and the use and necessity of 

 them in reasoning. He first expressed the dis- 

 tinction between primary and secondary qualities, 

 though the ideas implied in this distinction seem 

 to have been in some measure understood by Des 

 Cartes. And, finally, Mr. Locke had much merit 

 peculiar to himself, in exhibiting the ambiguity of 

 words, and by this means solving many difficult 



