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, thanks.)