LIGHT MERELY VISIBLE. 267 



can have no reason to doubt that the colours of 

 nature are all produced by the sunbeams. But, 

 in consequence of the great rapidity with which 

 light moves, we must not confound the manner 

 in which we see painters make up their shades of 

 colour by mixing variously- coloured substances, 

 with the mode in which the colours of nature are 

 produced. The light reveals the colours, but we 

 are not warranted in saying that it makes them; 

 for though, by means of a common triangular 

 prism, we decompose a beam of light into the 

 most perfect spectrum, and keep that spectrum 

 ever so long on the same identical piece of white 

 paper, or any other surface, whatever may be its 

 colour, we shall never be able to find a trace of 

 the spectrum on the paper, or other surface, after 

 we remove it out of the light which the prism 

 decomposes. 



Now it is evident that, if the remaining colours 

 of the sunbeams did not in some way act upon the 

 surface, which gives out any particular colour, 

 the surface that shows any colour under the spec- 

 trum, would show the same whether the spectrum 

 were there or not, and as the same colour remains 

 on the surface after the spectrum has been removed, 

 that was there before the spectrum was thrown 

 upon it, it is just as evident that every coloured 

 surface must have some peculiar state or pro- 

 perty which disposes it to show its particular 

 colour. 



Hence it is evident that colour, and that 

 which we usually call light, is not a being or thing 

 of any kind, but merely a relation between one 

 surface and a reflection from another surface ; that 

 being the case, we cannot regard light as in any 

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