76 HUME ii 



Under " impressions " he includes " all our 

 more lively perceptions, when we hear, see, feel, 

 love, or will; " in other words, " all our sensations, 

 passions, and emotions, as they make their first 

 appearance in the soul " (I. p. 15). 



" Ideas," on the other hand, are the faint 

 images of impressions in thinking and reasoning, 

 or of antecedent ideas. . 



Both impressions and ideas may be either 

 simple, when they are incapable of further analy- 

 sis, or complex, when they may be resolved into 

 simpler constituents. All simple ideas are exact 

 copies of impressions; but, in complex ideas, the 

 arrangement of simple constituents may be dif- 

 ferent from that of the impressions of which those 

 simple ideas are copies. 



Thus the colours red and blue and the odour of 

 a rose, are simple impressions; while the ideas of 

 blue, of red, and of rose-odour are simple copies of 

 these impressions. But a red rose gives us a 

 complex impression, capable of resolution into the 

 simple impressions of red colour, rose-scent, and 

 numerous others; and we may have a complex 

 idea, which is an accurate, though faint, copy of 

 this complex impression. Once in possession of 

 the ideas of a red rose and of the colour blue, we 

 may,, in imagination, substitute blue for red; and 

 thus obtain a complex idea of a blue rose, which 

 is not an actual copy of any complex impression, 

 though all its elements are such copies. 



