32 THEORETICAL BIOLOGY 



a blue-green paint with a yellow-green, the mixture is green, 

 even when, in the colours we started with, the green admix- 

 ture was so faint as to be scarcely perceptible. The reason 

 for this is that blue and yellow when mixed give white, and 

 only the green comes out as colour. 



We call the pairs of colours that unite to give white, 

 complementary colours. Every coloured surface has the 

 power to call forth its complementary colour in its environ- 

 ment, and also, when its own colour disappears, to take on 

 the complementary colour. To explain this, the physiologists 

 are obliged to assume special arrangements in the retina of 

 the human eye, since physical theory is at complete variance 

 with this phenomenon. The reciprocal reaction of coloured 

 surfaces plays an important part in nature : for instance, 

 the shadows of trees on a yellow road seem blue, and 

 cloud-shadows on the blue-green sea appear reddish. 



Nowadays there can no longer be any doubt that in the 

 distribution of colours in the world the subject plays the 

 decisive role. But feeling with Goethe, we can well imagine 

 the scorn he must have had for the physicist who utterly 

 refused to consider such a thing. 



It is worth while to pause for a moment and inquire why 

 it is that physics is bound to deny the theory. The official 

 physical theory stands or falls with the dogma of the absolute 

 reality of space. According to this theory, one object cannot 

 affect another except by means of actual changes in space". 

 The complementary effect of coloured surfaces, however, is 

 nothing of the kind ; nothing at all happens in the objective 

 world that could be accounted for in such a way. For 

 example, two coloured surfaces so placed that there can be 

 no mutual irradiation, nevertheless influence one another. 

 On the other hand, there are in the subject actions and 

 reactions according to law, which account for the com- 

 plementary phenomena. 



