Hay's mapping of colour onto musical notes, a diagram from his The Laws of Harmonious Colouring (1838).
Featured on PDR in the essay Music of the Squares: David Ramsay Hay and the Reinvention of Pythagorean Aesthetics
Understanding the same laws to apply to both visual and aural beauty, David Ramsay Hay thought it possible not only to analyse such visual wonders as the Parthenon in terms of music theory, but also to identify their corresponding musical harmonies and melodies. Carmel Raz on the Scottish artist’s original, idiosyncratic, and occasionally bewildering aesthetics.