254 ELEMENTS OF SCIENCE 



possess in order to be able to perform any intellectual 

 act whatever. Most persons never think about it, and 

 many readers may be surprised that they have had it all 

 along without ever recognising it. But though not 

 itself at first adverted to, it is by that idea alone that all 

 other ideas are intelligible to us as light, though itself 

 unseen, makes all other things visible. If we cannot 

 perceive that anything "is," we cannot, of course, perceive 

 anything at all. But ordinarily, and especially in the 

 beginning of our intellectual career, our attention is 

 directed to real concrete external objects, in perceiving 

 any one of which our minds acquire two distinct expe- 

 riences: (i) the intellectual apprehension of the object 

 perceived ; and (2) the sensations, ordinarily unnoticed, 

 which serve to make that object known to us. If 

 the reader will consider for himself the action of his 

 own mind, he will perceive such to be the case ; thus, for 

 example, should he, when reading this, have lately met 

 a carriage with some friends of his in it, let him ask 

 himself what was present to his mind at the time. He 

 will say that the presence of the carriage and his friends 

 was what he directly perceived. Of course, in order to 

 perceive them, he must have experienced certain sensa- 

 tions : his eyes saw various patches of different colours, 

 and his ears heard the sound produced by the wheels, 

 the horse's hoofs, and his friends' voices. But he never 

 adverted to these sensations at the time he felt them, 

 though he can turn his mind back and recognise that 

 they were then present to his sensitive faculty. His 

 intellect was not occupied about his sensations when he 

 perceived his friends, so that his sensations, though 

 affecting his sensitive faculty, were not themselves 

 perceived. Sensations are the means, not the object of 

 perception. They hide themselves from our notice, in 



