The succession of colors in the rainbow remains a metaphysical mystery to me in light of secondaries. Green comes into being from yellow and blue, and so it makes sense that it is located between yellow and blue (YGB) in the spectrum. The same thing goes for orange, which is between red and yellow (ROY). Yet, if violet arises from red and blue, why is violet not between red and blue? Why is red so far away from blue (R-OYG-B), and why does there have to be an intermediary color called indigo between blue and violet (B-I-V)? Is indigo, therefore, a tertiary of blue and violet? If so, should not indigo and blue-violet be identical rather than indigo being described as a dark, midnight blue?

The only answer I can think of is that there is a second, invisible, circular spectrum superimposed on the first spectrum. And, actually, there may be more than one--so much more that the circle is really a sphere, except that we have been brainwashed to view rainbows as two-dimensional.