The Jesuit priest Louis-Bertrand Castel had his hour of fame in the 18th century thanks to his ocular harpsichord.
Starting from the idea of a physical analogy between sound and color, Castel conceived of a harpsichord that would diffuse a music of colors organized into a scale on the basis of their natural correspondence with sounds. In this way he sought to reveal the rational principles that determine the order of nature, grounding art in reason. Art would thus bear witness to a divine intelligence compatible with reason, and the music of colors would be a form of revelation.
In addition, this development would rescue people from boredom, the languor that takes away their feeling of existing, by ensuring continuous movement and surprise, renewing the pleasure of variety, and satisfying the natural inconstancy that goads them relentlessly to seek other objects of pleasure. From this to the preaching of a libertine art was a matter of a single step, which Castel took without realizing it. For him, amusement had achieved a respected place in the world.
This according to Le Père Castel et le clavecin oculaire by Corinna Gepner (Paris: Honoré Champion, 2014).
Today is Castel’s 330th birthday! Above, a caricature of Père Castel and his instrument by Charles Germain de Saint Aubin; below, a brief discussion.