Gray

[nikola]

Gray color is formed from the mixing of opposite color, black and white. Also, by mixing the primary colors red, yellow, blue.

And if you take a ball, placed on two poles (north, south) black and white,
and the equator spectral colors (red, orange, yellow, green, blue, indigo, violet).
It is understandable that the movement of the spectral colors (the ball) to the poles
in one case Bleaching color, reaching up to white, and the other, obscures the move to black. In the center of the world black and white form the gray
same happens with the spectral colors.
  You can dare to conclude. There are spectral colors, white,
black. Everything else is shades of gray.