LECTURE XIV. 



EXPERIMENTAL PHILOSOPHY. 



COLOURS. 



I HAVE explained the nature of vision, and 

 that it is by means of the rays of light which 

 are sent from the different objects that sur- 

 round us to our eyes that they are rendered 

 visible. But you are yet at a loss to understand 

 whence proceed the infinite variety of colours in 

 which the whole creation is superbly arrayed. 

 You must be rendered sensible of these colours 

 by means of the light : but you will be surprised 

 to learn that the colours are not in the things, 

 but in the light itself; and that every beam or 

 pencil of light is composed of particles of different 

 colours. " The blushing beauties of the rose, 

 the modest blue of the violet," says Goldsmith, 

 "are not in the flowers themselves, but in the 

 light that adorns them: odour, softness, and 

 beauty of figure, are their own ; but it is light 

 alone that dresses them up in those robes which 

 shame the monarch's glory." 



You must have observed yourselves, that the 

 colours of objects are essentially altered by the 

 light in which they are seen. The colours of 



