The entire issue of the newspaper "Sanktpeterburgskie vedomosti", No 35, 29 April, 1742 is dedicated to the coronation of Elizabeth I.Among other news items is the following brief communication from the world of science:
"This morning the Imperial Academy of Sciences held a public meeting to bring the festivities to a close. Mr Kraft, professor of physics, delivered a speech on the eye pleasing clavichord recently invented in France. He also endeavored to resolve on a physical basis the following question: Can colours, if arranged in a particular manner, provide a deaf person with the same type of enjoyment as we experience when our ears perceive a harmonious consonance of musical tones? This was answered by Doctor Weitbrecht, professor of physiology..."
These "Speeches, delivered during the public meeting of the Imperial Academy of Sciences on 29 April 1742" have been preserved. Up to now they have not been given due attention, having received only brief mention . However, familiarity with the "Speeches" makes it evident that they deserve a more thorough consideration - especially in the light of the present revival of interest in the idea of "visual" music.
What is this "clavichord oculaire", devised by the French Jesuit monk L.-B.Castel, known for his work in mathematics and physics? For clarification one must turn to even more distant times.
Pythagoras (6th century B.C.), through his experiments with string, discovered that the structure of the musical scale is in keeping with strict numerical proportions. As is obvious today, Pythagoras's discovery represented for European science in general the first physical law to be expressed in an explicit mathematical form . Thus it is not surprising that, considering this law as unique and universal, Pythagoreans used the proportions of musical acoustics to explain all other phenomena of nature, including Cosmos, which they thought of as a huge harmonically tuned instrument of divine origin. According to the Pythagoreans, all the "planets" (including both the Moon and the Sun) rotated around the Earth along orbits proportional to the gradations of the scale, continually producing the inaudible sounds of the so called "music of spheres". The students of Pythagoras even managed to obtain concrete data about this extraterrestrial space music. According to one version, Saturn produced a sound similar to the note B, Jupiter - C, Mars - D, the Sun - E, Mercury - F, Venus - G, the Moon - A. It is amazing that a similar type of musical cosmology was developed, independently of the Pythagoreans, in ancient Oriental cultures (principally in India and in China ). This yet again testifies to the existence of a distinct unity in the development of diverse cultures .During the Middle Ages and the Renaissance, the "music of the spheres" experienced a revival. Its most noticeable recurrence was in the teaching by J.Kepler who, in his "Harmony of the Universe" ("Harmonices Mundi", 1619), which contained his three famous laws, revealed again and "definitively" the score of this planetary symphony, this time, however, not in its geocentric, but in its heliocentric version .
Isaac Newton, who fell under the spell of Kepler's "Harmony of the Universe", compelled himself to "hear" echoes of "music of spheres" in the light spectrum as well, dividing it specifically into seven colours, and not any other number of colours (even though in Europe at the time it was customary to single out five independent colours; other people, by the way, even today divide the spectrum differently).
Newton was by no means thinking of creating a new art on the basis of this analogy of "seven tones of the scale - seven colours of the spectrum" (a fortuitous analogy as we see it, devoid of any true physical content). This was left to Castel (1688 - 1757) who, after reading Newton's "Optics", proposed devising a "colour clavichord" which, when its keys were pressed, would produce simultaneously both the sound and the colour "corresponding" to the given tone. His project brought about a storm of discussions in scientific circles all over Europe. His extraordinary ideas were received favorably by the composers Rameau, Telemann, Gretry. Critics of Castel's "musique oculaire" included such celebrated contemporaries as Rousseau, d'Alembert and Diderot, who expressed their sharply negative attitudes toward his ideas in their famous Encyclopaedia. Voltaire sarcastically nicknamed him the "Don Quixote of mathematics".
The above-mentioned academicians from St.Petersburg subjected Castel's "musique oculaire" to a thorough analysis. The discussions were based on Castel's well-known publications in French journals as well as on a certain letter "from Paris", which had been received, as reported by Kraft, by the Russian Academy of Sciences in 1741, exactly one year earlier. (Judging by the evidence, Russia at the time was not familiar with Castel's principal work  nor with the book of his interpreter G.F.Telemann ).
Kraft began his criticism by turning to Galileo, who had noted a definite relationship between the observed oscillations of the pendulum and its length - an indisputable fact yet one that irritated Kraft in that Galileo used relationships and terms such as "fifth" and "octave". "It is true", reasoned Kraft, "that he has presented an agreement, but it is one that is lifeless, neither alive nor musical. Instead of a living and fullblooded body there are dead and dry bones; instead of magnificent palaces, a base shelter of branches". In his criticism Kraft, speaking as a physicist, argued seriously that the low frequency of the oscillations of Galileo's pendulum accounted for their inaudibility and consequently the impossibility of admitting them into the realm of music. And he linked the emergence of an audible sound with the frequent "vibrations" of the string. He saw the ideas of transferring musical proportions into the realm of colours as providing an even greater basis for criticism. "I do not believe", he said, "that there would exist a physicist who could prove that light also possesses vibratory motions" (i.e. Kraft denied light its wave property). As a result, since there is no basis for proportion in "vibrations", since "there is no fifth", Kraft concludes, "there is no music".
Nor did Kraft ignore the abovementioned fact of dividing the spectrum into seven colours, which had been undertaken by Newton. However, attempting to justify Newton, he pointed out that "we do not immediately perceive" the zones dividing the spectrum into separate colours, but rather discover them "by means of our mind", and that Newton himself "did not think of establishing musical agreement from colours". One might just as well, maintained Kraft, imagine a person "who on sheets of paper would write down numbers forming a harmonic or some other progression and then after shuffling them, would expect them to yield some form of musical enjoyment". Kraft's arguments remain valid even today.
The arguments of the second speaker, academician I.Weitbrecht, "doctor of medicine and professor of physiology", were more fundamental. He spoke more sharply than Kraft, who had been fascinated at times, during this discussion, by physical analogies and often had been "under the influence" of Castel, arguing about insignificant details. "I have always been of the opinion", said Weitbrecht, as he took the floor, "that it is easier and simpler for a legless man to learn to walk on his hands than for us to perceive with our eyes sounds presented in various colours and to perceive them with the very same sweetness with which they enter our ears".
Discriminating between the abilities to see, hear and reason, Weitbrecht backed Kraft in that, by its physical nature, colour cannot affect eyesight the way sound affects hearing. He also pointed out that the organs of vision and of hearing have different structures, which rules out the possibility for them to affect "our soul" in the same way. And finally he came to his main argument that it is impossible for "our thoughts about diverse and specific objects, represented in different ways, to evoke the same or similar reactions (either positive or negative)".
Thus he arrived at the following conclusion: "Accords in music are pleasing and colors are also pleasing, but in a completely different way". Music is constructed on the change of tones, whereas the effect of colour is based on constancy:"A single colour may be quite pleasant by itself, yet, as the saying goes, one string does not make much noise. And, vice versa, their frequent and rapid change will sooner dazzle our eyes than provide enjoyment. So, when desiring to amuse the eyes by the hearing, we will undoubtedly get a revolt".
Weitbrecht believed that if Galileo did wish to hear "music" in the oscillations of the pendulum, then this music was "imaginary and philosophical". This is precisely how Castel regarded his own idea, for he considered himself a philosopher and readily renounced his fame as the inventor of the new instrument.
Until the end of the nineteenth century, it was a matter dealing only with the idea of visual music (and not with the art itself). I should also point out that for Castel's supporters and critics this idea was first and foremost a philosophical problem and more specifically, the one that concerned the natural sciences. Castel's ideas of seeing sounds and of a "music for eyes", which he intended only for the "philosophical" eye, not merely became known as fancies of the mind  or as the symbol of the absurd, but turned into a touchstone of sorts on which the blade of polemics was sharpened. It was used by: Condillac in his arguments with the rationalist school in philosophy ("Treatise on systems"); Diderot and d'Alembert arguing with Rameau about whether harmony is a science (Encyclopaedia); Rousseau supporting the "encyclopaedists" in their criticism of the "mathematicization" of art and pointing to the difference in the perception of sound and colour according to the role played by, to use current terminology, the "reflex to the relation of the irritants" ("A study on the origin of language"); Goethe and Buffon pointing to the fortuity of Newton's analogy and stressing that, in the nature and for human organs, sound and colour appear as independent processes ("Theory of colour" and "Observation of random colours", respectively); it becomes Herder's argument in his dispute with Lessing concerning the difference between "action" and "consequence" in classifying the arts ("Critical scaffolding or considerations relating to the science of the beautiful and art, on the basis of recent investigations"); etc.
It is plain to us today that Castel's ideas are non-artistic and non-aesthetic in content and natural-philosophical by origin, following the course of a metaphysical quest for confirmation of the unity of the universe, apprehending it as the discovery of universal constants and analogies of a Pythagorean kind. All the opponents of Castel mentioned above, both foreign and Russian, analyzed and criticized in the main this natural-philosophical analogy of "spectrum-scale", the idea of the simple mechanistic transformation of music into colour. At the same time, however, many of them questioned the hypothetical possibility of seeing music altogether; many, but not all. Weitbrecht, although he had leveled harsh criticism at Castel, concluded his speech with the following words "It may easily come about that some kind of enjoyment will be found for our eyes that will delight us no less than music ..."
M.V.Lomonosov, who was present at this memorable session, also did not ignore this problem. He subsequently noted in one of his physics papers: "Colours agree amazingly with music ..." . And in the ode commemorating the anniversary of the coronation of empress Elizabeth I, he introduced the following lines, which were incomprehensible to the readers:
Hush, ye flaming sounds,
Stop shaking light...
Soon after the discussion of Castel's ideas, L.Eiler, another academician from Petersburg, presented his special investigation "Physical observations relating to the propagation of sound and light", which contained meticulous computations of the frequencies of musical tones. In consequence, he is commonly regarded as an adherent of Castel's ideas. But in his papers he did not draw any analogies between definite sounds and colours, although, for the first time in science, the difference in colours was related to the difference in the frequency of the corresponding vibrations of ether . (By the way, Castel's followers, if they had known this fact, could have deprived Kraft of his principal critical argument). Naturally, he did not have thoughts of devising "musique oculaire". Comparing sound and light was necessary only for comparing their methods of propagation. Of course, light propagates in a different medium, and if air were as "thin and elastic" as ether, maintained Eiler, sound would have a speed of propagation equal to that of light.
It is of interest to pursue further the destiny of Castel's ideas in Russia and to compare the new criticism with the conclusions of the Petersburg academicians. For Russian readers another significant impetus, stimulating their interest in "musique oculaire", was the book by the German writer K. Eckartshausen, "The Key to the Mysteries of Nature", which was widely known in Europe during the late eighteenth century and was translated into Russian many times. The film director S.Eisenstem cites vast passages of it his "The Vertical Editing":"For a long time I have been investigating the harmony of all sensuous impressions. To make it more obvious, I have amended the musical machine, invented by Pater Castel, so as to make it possible to produce all chords of colour exactly as chords of tones. Here is a description of the machine. I had some glass cylinders, made all equal in their dimensions, and half an inch in diameter, and filled them with coloured liquids in keeping with the theory of colours. I arranged these cylinders just as strings in a clavichord are positioned, dividing tints of colour in the same way that tones are divided. The cylinders were closed by copper flaps placed behind them. As the flaps rose, colours were revealed... The clavichord was lit from behind by tall candles. It is impossible to describe the beauty of the emerging colours, for they surpass the most valuable jewels. He who was the first to speak of a music for the eyes was held in derision..., nevertheless this did not frighten me" .
But the principle proposed by Eckartshausen differs substantially from the ideas of Castel. Eckartshausen abandoned speculative physical analogies: "Just as musical tones should be in accord with the author's narration in a melodrama", he supposed, "so too should colours correspond to words", for "colours can express the sentiments of the soul..."
The Italian theatre artist P.Gonzaga (1751 - 1831), who had worked for many years in Russia and published his work "Musique Oculaire"  here, came even closer to an artistic treatment of the problem of visual music. In his numerous productions, he sought to give a plastic presentation of music and drama, attempting to obtain a harmonious audio-visual unity; and in some performances, even the changing of scenery occurred in accordance with the music. He stated that the musical element was predominant in the theatrical culture of his time and noted the lack of interest in the visible, which, so he thought, had a "music" of its own. Gonzaga did not rule out the existence of analogies between the spectrum and the octave, but he considered it wrong to use them to produce "musique oculaire" in accordance with Castel's principle:"[Castel] did not take into consideration that colours act in space while sounds act in time, that our ears like to perceive sounds in succession, one after the other, whereas our eyes like to observe colours arranged simultaneously side by side. He failed to appreciate that this momentary process is contrary to the peculiarities of vision, which wishes to dwell on things and finds it just as difficult to grasp the instantaneous relationships between objects that follow one after the other as it would be for the ear to perceive persistent non-alternating sounds."
(We may note that this has much in common with the anti-Castel arguments of Rousseau, Weitbrecht and Herder). Gonzaga compared space and colour to musical accents and tones and believed that for making visual music "spatial rhythm and colour modulations are required". He proposed to divide space in a manner similar to the division of time.
If Castel's works became widely known in Europe in due time and his analogy, his "music of colour" became even a sort of trite metaphor in the literature and poetry of the eighteenth and nineteenth centuries, then Gonzaga's contribution to the development of the concept of visual music is known but little among specialists in aesthetics and musicologists, especially among foreign ones. It was Gonzaga who was the first to point to the feasibility of an actual "musical" vision. At the same time, he realized the triviality and emptiness of Castel's colour modulations. He compared music with the richest realm of visible shapes, and it was with contours, drawings, that he compared, as did Rousseau, melody - the principal "information carrier" in music. He could also discern the hypothetical possibility of realizing the "music for eyes'" metaphor when paying attention to the unique artificial light-dynamic phenomenon, specially intended for art purposes - a fireworks. Gonzaga believed that fireworks possess a striking similarity to music in the proper sense of the word:"Fireworks contain, along with the other musical characteristics already noted, the great advantage of never being constant, durable; combinations of shapes and colours develop in time, undergo changes and vanish rapidly, similar to tones modulations and musical rhythm. Consecutive development and motion are essential here and contribute to the momentary enjoyment of changes. And, lastly, this is just the optical clavichord and, by its very essence, music for the eyes..."
This period of direct critical appraisal of Castel's ideas in Russia can be regarded as finished. As shown above, these ideas were called into being not because of the requirements of art, but rather because of the attitude of the past centuries that was ready to treat music as "one of the applications of mathematics" (as V.F.Odoevsky put it). This detailed account of Castel and his critics is not presented here merely to provide a complete historical background. We are dealing with an amazing experiment staged by history: Castel with his theory (even though it has no direct bearing on art) literally forced his contemporaries, though prematurely, and as if "accidentally", to state their opinions on the very idea of visual music. True, many of his critics could not go by themselves beyond the framework of metaphysical speculations; however, the explanations as to why Castel was wrong contained many correct observations.
The concept of instrumental "music for eyes", lacking the stimulus of genuine aesthetic inquiry and the technical prerequisites for testing, stiffened in a scholastic stupor and developed no further, although in Russia as well as in the West from time to time information was published about either Castel himself (in reference books) or fresh discoveries of the idea of the "color clavichord" . But the largest publication along this line at the beginning of the nineteenth century was a satirical article that derided not only Castel but his supporters - Gretry, etc. . Russian readers were familiar with the later criticisms of Castel contained in the works of J.W.Goethe, H.Helmholtz, W.Ostwald, M.Mendelssohn. T.Seemann's musicomorphous concept of pictorial colouring had revived a short lived interest in the problem; it had been popularized in various forms by Russia's own followers of Castel up until 1910, the year the composer A.N.Scriabin created "Prometheus", the first light-musical composition in the world [42-47]. They are mentioned here merely to illustrate the belated and unmotivated recurrence of mechanicalism and reductionism in art. Already by the late nineteenth century, after electricity had been mastered and attempts were being made to build working "colour organs", spectators could see for themselves that the flashing of colours according to the "law" of Newton (or Castel, Seemann, etc.) in no way coincided with the artistic and emotional influence of the music that had been "translated" into colour: the experiments of B.Bishop in the USA , B.Taillet in France, A.Rimington in Britain, A.Scriabin in Russia. The conclusions of the Petersburg academicians proved prophetic.
It becomes evident that the laws of "audio-visual harmony" should be sought not in the sphere of physical extra-human analogies , but on the basis of comparison of the physiological, psychological and, ultimately, aesthetic influence of light and colour (which correspondingly characterizes the notions of "audio-visual unity" and "audio-visual harmony" as a gnoseological category). And it is here that real possibilities exist for the advancement of the ideas of "visual music", as manifest in the current practice of the so-called music-kinetic art [49-53].
REFERENCES AND NOTES
Published in Leonardo, vol.21, N4, pp. 392-396, 1988