Wittgenstein on color, remark #11

Someone who is familiar with reddish-green should be in a position to produce a color series which starts with red and ends with green and which perhaps even for us constitutes a continuous transition between the two. We would then discover at the point where we always see the same shade, e.g. of brown, this person sees brown and sometimes reddish-green. It may be, for example, that he can differentiate between the colors of two chemical compounds that seem to us to be the same color and he calls one brown and the other reddish-green.