60 ON COLOUR. 



Taet I. 



it. Thus blue and red have a very different action on each 

 other from green and red; as these last have from blue 

 and orange ; though in the two last cases the colours green 

 and red, and blue and orange, are accidental to each other. 

 Blue and orange, which are accidental colours, are a harmo- 

 nious contrast; but red and green, or yellow and purple, are not 

 necessarily so because they are also accidental colours. (See 

 Sect. VI.) We must therefore understand which colours agree 

 by contrast, which by analogy, and which tend to diminish, or 

 otherwise alter each other's effect ; for some of these are apt to 

 be confounded, and a very fallacious doctrine has been pro- 

 pounded — that the union of one of the primaries with its acci- 

 dental colour is analogous in effect to that of the same 

 primary with its two companions ; as, for instance, that red 

 with green has the same effect as red with blue and yellow. 



It is true that white light consists of all the three, and it 

 is not till it has been decomposed that they are distinctly and 

 separately presented to the eye ; but in looking at white light 

 we do not distinguish the red, blue, and yellow ; otherwise, a 

 white glass window might pretend to the possession of the 

 three colours. No one, however, will allow his fancy to go so 

 far as to imagine that in white he sees the three primary 

 hues ; and yet it is not more inconsistent than to consider 

 green the same as blue and yellow, or to say, as some 

 have, that when green is put with red we then have the 

 three primary colours — we have in reality one primary and 

 one secondary; and to show the difference of the effect of 

 two colours when used singly and when united as a compound 

 or secondary, we need merely place red and yellow with 

 green, and orange with green ; the former an imperfect, the 

 latter a very harmonious, combination. (See Sect. XVIII.) 



It is to the eye that the several colours must distinctly 

 appear. It is not enough to know that theoretically they are 

 all there ; and green is not only to the eye a new colour, 



