“Musicians have appropriated the word color principally to describe the sensuous charm of their art. Hue is used to denote the shifts in effect that followed varous changes in timbre. Tone-color is a synonym for timbre. In truth, this quality in music (timbre), aside from what are called intensity and pitch, is easily associated with hue. For color has timbre, fullness, delicacy, volume, softness.”

—Adrian Bernard Klein, from Colour-Music, The Art of Light, 1930, as quoted by Tom Douglas Jones in The Art of Light and Color, 1972.