the ocular harpsichord of louis-bertrand castel - Gewina

Castel's ocular harpsichord 39
the name of ocular harpsichord.
As Kriiger wholeheartedly defended Newton's theory of optics in his Naturlehre,
he might, especially in Germany, be partly responsible for the fact that in the
latter half of the eighteenth century the idea of colour harmony was often
thought to have been advocated by Newton himself.
Initial reception: scientific scepsis and artistic affinity
Scientific scepsis
Castel's defence of his colour music was detailed enough to invite serious
criticism. There was hardly any of it, however, after its first announcement in
1725. Only one comment appeared in print, written by an anonymous "Philosophc
Gascon", who accused Castel of confounding "two things which all philosophers
distinguish, and which are indeed as apart as mind and body; you confound
the sensations that the soul experiences with the occasional causes of
these sensations".** Even if light and sound were both vibrational phenomena,
the anatomical differences between eye and ear were sure to destroy any
commensurability of optical and acoustical sensations. Castel never really
answered this line of criticism, which would be voiced by later writers as well;
apart from his mechanistic argument that all senses can only transmit the
impulses they receive from outside into the sensorium, his simple conviction that
colours delight the soul apparently counted sufficiently against it.
It was only in 1735, after the publication of Castel's "Nouvelles expdriences
d'optique et d'acoustiquc", that the ocular harpsichord fully entered the public
arena. In the following five or ten years Castel must have been at the height of
Kriiger, Naturlehre, 2nd ed.. vol. 1, p. 627; 3rd ed., vol. 1, pp. 684-685: "Wer die schonen
Farben, welche durch das Prisma entstehen. bctrachtet, den kan man leicht auf den Einfall bringen,
daU cs wohl eben so moglich sey, das Auge durch Abwechsclung und Vermischung der sieben
Farben, als das Ohr durch die sieben Tone zu vergniigen. Ich habe daher eine solche Maschine
angegeben ... welche des Namens eines Farbcnclavecj'mbels nicht unwiirdig ist." The last part of the
sentence, calling the instrument an ocular harpsichord, was only added in the third edition. There
were later posthumous editions up till 1777. In 1748 Kriiger published a description of his
instrument in German, which did not contain anything new, except that it showed that Kriiger could
be equally enthusiastic about colour music as Castel. What is interesting, however, is that Kriiger
stated that he had previously worked as an organ builder. See Kruger, "Anmerkungen."
Mercure de France, May 1726, p. 933: "vous confondez deux choses que tous les Philosophes
distinguent, & qui sont effectivement aussi distinguees, que I'esprit I'est du corps; vous confondez
les sensations que I'ame ^prouve avec les causes occasionnclles de ccs sensations".