“The north pole is white. The south pole is black. The equator is a circuit of middle reds, yellows, greens, blues, and purples. Parallels above the equator describe this circuit in lighter values, and parallels below trace it in darker values. The vertical axis joining black and white is a neutral scale of gray values, while perpendiculars to it are scales of Chroma. Thus, our color notions may be brought into orderly relation by the color sphere. Any color describes its color quality, light and strength, by its place in the combined scales of Hue, Value, and Chroma.”

—Albert Munsell, describing his color sphere in A Color Notation, 11th edition, 1961.