Note 170 — Chapter VI

The compounding of colors may be dealt with in an identical way. Helmholtz has shown that if green light and red light fall simultaneously on the retina, we see the color yellow. The mind-stuff theory would interpret this as a ease where the feeling green and the feeling red 'combine' into the tertium quid of feeling, yellow. What really occurs is no doubt that a third kind of nerve-process is set up when the combined lights impinge on the retina,—not simply the process of red plus the process of green, but something quite different from both or either. Of course, then, there are no feelings, either of red or of green, present to the mind at all; but the feeling of yellow which is there, answers as directly to the nerve-process which momentarily then exists, as the feelings of green and red would answer to their respective nerve-processes did the latter happen to be taking place.