the ocular harpsichord of louis-bertrand castel - Gewina

Castel's ocular harpsichord 49
probably was in the late 1740s that Diderot paid a visit to Castel's workshop, as
many others had done before him. The description of this visit Diderot included
in his Lettre sur les sourds et muets, published in 1751. Diderot, however, had
prepared himself better than the others, in bringing with him a deaf-mute: "I
imagined that if there was anyone on earth who was to receive any pleasure
from ocular music, and anyone who could judge it impartially, it was a deafmute
by birth.""^
As is clear from his account, the reaction of the deaf-mute pleased Diderot
and perhaps it played a part in winning him over to Castel's views. It was
obvious, said Diderot, that there was no way of explaining to the deaf-mute
anything about the nature and the marvelous properties of the harpsichord; since he had no
idea of sound, what he understood of the ocular instrument assuredly had no relation to music,
and the purpose of this machine was to him as incomprehensible as the use that we make of
our speech organs. Then what did he think? And what basis was there for the admiration to
which he succumbed when he saw the gamut of Father Castel? ... My deaf imagined that this
inventor of genius was equally deaf and mute; that he used his harpsichord to communicate
with other people; that each colour shade on the keyboard had the value of one of the letters
of the alphabet; and that by way of the keys and the agility of his fingers, he combined these
letters and formed words, phrases, indeed a whole conversation in colours.
Now, suddenly, the deaf-mute believed himself to comprehend what music was:
"He gathered that music was a special way of communicating thought, and that
the instruments, the fiddles, the violins, the trumpets, were, in our hands,
another type of speech organ." Diderot thought this very clever of the deaf-mute:
"If he had perhaps not exactly chanced upon what [music] was, he had almost
chanced upon what it should be."*'
Given this appreciation, one would surely expect Diderot to say something
completes, vol. 4, p. 203.
Diderot, Oeuvres completes, vol. 1. pp. 356-357: "J'imaginai que s'il y avail un etre au monde
qui dflt prendre quelque plaisir a la musique oculaire, et qui piit en juger sans prevention, c'etait
un sourd el muet de naissance."
Ibid., pp. 357-358; "qu'il n'etait pas possible de lui rien communiquer sur la nature et les
propriit^s merveilleuses du clavecin; que n'ayant aucune idee du son, celles qu'il prenait de
I'instrument oculaire n'^taient assurement pas relatives a la musique, et que la destination de
cette machine lui itait tout aussi incomprehensible que I'usage que nous faisons des organes de la
parole. Que pensait-il done? el quel etait le fondement de I'admiration dans laquelle il tomba, a
I'aspect des 6ventails du Pere Castel? ... Mon sourd s'imagina que ce genie inventeur itait sourd
et muet aussi; que son clavecin lui servait a converser avec les autres hommes; que chaque nuance
avail sur le clavier la valeur d'une des lettres de I'alphabet; et qu'a I'aide des touches et de
I'agilite des doigts, il combinait ces lettres, en formait des mots, des phrases; enfin, tout un
discours en couleurs ... II crut que la musique etait une fa^on particuliere de communiquer la
pens^e, et que les instruments, les vielles, les violons, les trompettes etaient, entre nos mains,
d'autre organes de la paroles ... S'il ne rencontra pas exactement ce que c'itait, il rencontra
presque ce que ce devrait etre."