I made a small circular diagram of colors to-day. It reminded me of an experiment I have long wished to try, and have thought a good deal about. The idea was suggested by something I read, when a boy. I do not know where. It is what may be called the music of colours. I believe that colours are capable of affecting the mind, by combination, degree, and arrangement, like sound.
It is evident that there is an analogy between colour and sound; and with study and experiment it might be traced through all its ramifications. I am not aiming to prove the analogy, but to show that there is plausibility to the theory that an instrument might be constructed by which colour could be played, and which would give to those who had cultivated their taste in art, a pleasure like that given by music.
If I attempted to make an instrument, I should try to experiment with six colors and their semitints. The instrument might be played by means of keys, like those of a piano, except that, instead of their moving hammers to strike strings, they might lift, when struck, dark or black screens from before coloured compartments. Transparent compartments, with either sunlight or artificial light behind, would perhaps produce the most brilliant effect.
Cole’s diary entry for November 5, 1834