NATURE OP SENSATIONS. 225 



which are in the right position in relation to the place of 

 his eye. As he moves, he carries the apparent place of the 

 rainbow with him, and two persons standing side by side 

 see different bows in this sense, namely, that the rays that 

 produce the image in their organs of vision respectively do 

 not come from the same drops in the sky, and the bows are 

 not seen in the same position. It would perhaps be too 

 much to say that they do not see the same bow in any 

 sense, as the question in what the identity of a rainbow 

 really consists is one which might very naturally give rise 

 to great difference of opinion. 



It is, however, at any rate, perfectly sure that the rain- 

 bow is not an object real and fixed upon the cloud one 

 which we look at as we do at the cloud itself, or at the 

 moon, or a star. As a real existence, having the form and 

 appearance which it presents to our vision, it is an illusion. 

 It exists only in the eye of the one who looks upon it. 



Thus we see that many things which we are apt to con- 

 ceive of external objects having a real existence, or as 

 qualities of external objects, are, in reality, ideas or sensa- 

 tions in us. This truth applies to the impressions of the 

 other senses, such as the hearing, the taste, and the smell, 

 as well as to the sight. The words sweetness and saltness, 

 for example, denote sensations, and, of course, there can be 

 no sensation of any kind in sugar or salt. There can only 

 be that in them which excites these sensations on the 

 tongue which tastes them. 



It is evidently so in regard to all the impressions made 

 upon our senses. External objects communicate some 

 form of force to our organs by which certain sensations 

 are awakened in our minds, but these sensations do not 

 and can not exist in the objects themselves. 



Understood in this way, it is obviously true, as Law- 

 rence said, that there is no image in the mirror, no bow in 

 K2 



