And in addition, the classes are of different sizes. There is a such thing as yellow light, and red and green looks like it. There is no such thing as magenta l

And in addition, the classes are of different sizes. There is a such thing as yellow light, and red and green looks like it. There is no such thing as magenta light -- light is a linear spectrum, not a circle -- and yet red and purple together look like this nonexistent color. We see a continuity where there's a hard break.