In music there are big changes (such as a change in key) and small changes (such as where in a phrase an emphasis is placed). Changes in hue appear to the eye as large, relative to changes in tint or tone.

Scriabin held that each mode corresponded to a particular shade of colour, and each modulation to a nuance of this shade. Changes from the major into the minor could therefore be underlined by strong contrasts, on a visual as well as a chromatic level. This was one of the most important aspects of Scriabin's research into new areas of expression. His imagination had been stimulated by theosophical reading, and he dreamed of lighting up the whole of the concert hall to fit the music which was being played at the time. But in practice the performances of Prometheus which took place at the Carnegie Hall, New York, and the Bolshoi Theatre, Moscow, did not live up to his ambitions. The projection depended entirely on a small screen which was placed behind the orchestra, and they made very little impression on the audience.

Frank Popper, Origins and Development of Kinetic Art 1968, 157-8