Dirty Light - Marko Ciciliani

In another essential part of his Optics, Newton proved according to experiments that white
light consisted of different spectral colours that themselves can not be divided anymore. This
formed a clear break with Aristotle’s theory, which said that all colours were situated between
the extreme points that were formed by black and white. Although Grimaldi already made
this discovery earlier, it was through Newton that this new theory was commonly
acknowledged. Newton was also one of the first ones to arrange the colour spectrum in a
circle, probably in order to provide a logical explanation of the octave repetition in the
interval/colour analogy. This arrangement became the basis for later colour theories, which
were then extended to the ball-shaped arrangement.
1.1.7 Louis Bertrand Castel
Louis Bertrand Castel (1688-1757) spent more than 30 years working on the conception and
construction of a light organ. His idea was to find an analogous translation from the aural into
the visual domain. In 1740 he released Optique des couleurs, a book in which he laid out in
detail the results of his research. The similarity of the title to Newton’s Optics is hardly a
coincidence. Until that point Castel’s research in the field of sound-colour correlations was by
far the most thorough of its kind. He was also the first to give sound and colour full attention
without seeing it as only one aspect of a larger cosmologic complex of analogies.
All colour-pitch theories in the 16 th and 17 th century were based on modal scales. In his search
for analogies, Castel however referred to Jean-Philippe Rameau’s (1683-1764) Traité de
l’harmonie (1722). Rameau derived his theory from the overtone-scale and therefore only
considered the fifth, the major third and the minor third as perfect harmonies. He developed
functional harmony, which uses the tonic, dominant and subdominant as structurally
governing pillars. Underlying the idea of justifying the consonances according to the
overtones is the belief that “the essence of sounding material can be found in nature”. 34
Castel’s research started out with a comparison of the overtone scale with the light spectrum,
which results from filtering white light with a prism. He saw the common principle of sound
and light in the fact that both were based on vibration. He believed that the human senses
were structured in similar ways. Synaesthetic analogies as a spontaneous reaction are
however not of any relevance in his research.
The benefits that he pursued with his colour-pitch analogies were that:
• deaf people would be able to enjoy music and blind people paintings;
34 quoted after Sirker, Udo: “Joseph Saveurs musikakustische Untersuchungen. Ein Beitrag zur experimentellen
Forschung um 1700”, Cologne: Ars musica, musica scientia, (1980), 415.
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