HELMHOLTZ IN KONIGSBERG 



Helmholtz took up the subject. We have it on his 

 own authority, that his attention was directed to it by 

 a consideration of Miiller's doctrine of the specific 

 energy of nerves, mentioned at p. 13. In his speech 

 on receiving the Graefe medal, he said, ' Not being 

 inclined to describe in my lectures things I had not 

 myself seen, I made experiments in which I blended 

 the colours of the spectrum in pairs. To my aston- 

 ishment, I found that yellow and blue gave not green, 

 as was then supposed, but white. Yellow and blue 

 pigments, when mixed, no doubt gave green, and 

 until then the mixing of pigments was supposed to 

 produce the same effect as the mixing of the colours 

 of the spectrum. This observation not only at once 

 produced an important change in all the ordinarily ac- 

 cepted notions of colour mixture, but it also had an even 

 more important effect on my views. Two master minds 

 of the first rank, Goethe and David Brewster, were of 

 opinion that yellow and blue could be directly seen in 

 green. Their observations were made with pigments, 

 and they thought they could divide their perception 

 of the resulting colour into two parts, yellow and 

 blue, while in reality, as I was able to show, neither 

 were present. I was thus drawn over to the em- 

 pirical theory of perception, and it indicates even now 

 the contrast between my position in the theory of 

 colour perception and that of Hering and his followers, 

 who hold firmly to the opinion, that one can decom- 

 pose the perception into its component parts.' 

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