I love that this opens with a matter-of-fact statement that colors aren't real, just a phenomenon of perception. This has come up randomly in my life a few times and people always look at me like I'm stoned outta my mind.
The light hitting our eyes is not a phenomenon of perception. Each photon hitting our eyes has a certain wavelength, but the resulting color we see is a perception.
A related concept is sound vs psychoacoustics[1]. Sound is just pressure waves, but what we hear is a perception and has all sorts of aspects like masking[2]. The pressure waves contains two different signals but thanks to masking we might only perceive one.
Personally I think color constancy[3] really drives home that color is a perception and not something fundamental like the wavelength of photons.
