“All that visible objects have of magnificence and brilliance can be turned to the profit of the new clavessin. It is susceptible to all manner of embellishments. Gold and azure, metals and enamels, crystals, pearls, diamonds, embroideries, satins, velvets, etc., will not be only ornaments, but will form the body itself of the machine and be as its proper substance. For example, one can form the colors themselves with precious stones or counterfeits of the same color, the reds with garnets and rubies and carbuncles, the greens with emeralds, etc., and what brilliance and splendor a spectacle would possess where one could see appear from all parts and shine like stars, sometimes jacinths, and rubies, and sapphires—all these accompanied with the light of torches in an apartment all hung with mirrors. It would be an infinitely brilliant spectacle as an immobile decoration where everything would be in harmony, but what would it be like if movement and a regular, measured, harmonic, and quick movement animated all, giving it a sort of life? It would be a charm, a glory, a paradise!

One could perform a play, in which entered human figures, angelic figures, animals, reptiles, etc., or, again, one could demonstrate all the sequence of the elements of Euclid; one can give a play of flowers with variegated flowers, rose for the color of the roses, violet for the violet, etc., so arranged that each touch of the hand would represent a flower-bed and the sequence a mobile diversity of animated flower-beds. All that one can paint one can put into a moving picture, and vice versa, at the will of a clever player of the clavessin. I said that one could make as many color instruments as sound instruments, and one can make them according to a million tastes more different than those of ordinary music. Let all Paris have color clavessins up to 800,000!”

—Louis Bertrand Castel (1688–1757), describing his Clavessin Oculaire, the earliest known color-organ, in either La Musique en Couleurs, 1720, or L’Optique des Couleurs, 1740. As quoted by Tom Douglas Jones in The Art of Light and Color, 1972.