Nature of color and perception well described, Bruce:

the emission and absorption wavelengths of refracted and reflected light from a surface (ie, the “color” of that surface) are determined by physics and are what makes any given “color” that color. That is not subject to interpretation. It is thought that individual optical receptors (rods and cones in the eye) may respond to the same wavelength differently in different individuals. Here’s where it get tricky and your friend left out a lot of details. However, even though different eyes respond differently, your brain then “learns” that the input it receives for that wavelength is say PRR, 1930’s Freight car color. My brain learns the same thing even though the input from my receptors may differ some.

This excellent book covers color and perception for those who may want additional detail, and I do not think it has been recommended here before.
Vision and Art: The Biology of Seeing by Margaret Livingstone (2^nd Ed)

For perception of color, I also recommend Chapter 2 in Jeff Schewe's The Digital Print book on photography (his The Digital Negative is outstanding, too, but not specifically for color).

Rufus Cone
Bozeman, MT