What is the origin of "clear" as a primary colour?

Question

In The Land of Painted Caves by Jean M. Auel, the five primary colours are given as red, green, yellow, clear, and dark. The description in the book is:

Clear is the colour of the wind, the colour of water. Clear can show all colours, as when you look in a still pond and see a reflection, or when drops of rain sparkle in all colours when the sun comes out. Both Blue and White are aspects of Clear. When you look at wind, it is clear, but when you look into the sky, you see blue. Water in a lake, or in the Great Waters of the West, is often blue, and the water seen on glaciers is a deep, vivid blue.

I hadn't seen 'clear' described as a primary colour before. Is this used in other fantasy stories, or in actual historical texts (obviously they would have to be from a time after the one where the novel is set)?

(Please note I don't want a list of every time this has been used. If it's actually common, then the first example of its use is enough.)

Answer 1

According to linguists studying the color terms of multiple languages, there seems to be a clear progression as the number of basic colors increases. (See Wikipedia.)

If a language has only two color terms, they will represent light-warm (white, yellow, and red) and dark-cool (black, blue, and green).

One variation on five color-term languages is red, green, yellow, black/blue, and white. Given that Jean Auel does her research, she probably is using clear and dark to represent those last two concepts. That way, clear could represent both white and the color of water.

(Incidentally, English has eleven color terms [black, white, red, green, yellow, blue, brown, orange, pink, purple, and gray], and Russian and Italian have 12.)

Answer 2

A bit off-topic (since the question was about clear color), but the "dark" color actually has a very interesting biological connotation - certain species (such as jumping spiders or birds) have tetrachromatic vision - 4 different types of photoreceptors (as opposed to humans' 3 - RGB); the fourth is ultraviolet.

Answer 3

"Primary colour" is a bit flexible term; the standard RGB triad comes from the fact that we have 3 types of cone cells in eye, each sensitive to one of those colors (effectively). So well, extending it to also same-as-background and no-signal is more messing with the semantic of colour itself.

However, different eye construction will directly lead to a change in perception -- for instance any alien culture (capable of colour vision) would probably have other primary colours set -- yet I don't recall any use of this idea.