Kepler's The Harmonies of the World - A Transition from Astrology to Astronomy

Modern astronomy is regarded as a science, while modern astrology pertains to human affairs. However, both studies were once thought of as the same discipline. Astronomy has its roots in astrology, which is the study of the relationship said to exist between the changing positions of the heavenly bodies and the lives of people on the earth.

That astrological view formed the core of the musicomythological and musicomystical systems of ancient Mesopotamia, Greece, and other regions. The ratios, or mathematical relations, governing the music of the spheres (ethereal music believed by Pythagoreans and other ancients to be produced by the vibrations of the celestial spheres) also governed the inner being of each person. Remnants of that belief "survived through the Renaissance and indeed linger on to this day, in the form of astrology" (Grout, 29).

One of the principal figures in the transition from scientific astrology to modern pure science was the German astronomer Johannes Kepler (1571-1630).

Early in his career, he was greatly influenced by astrological ideas. For example, young Kepler "developed a mystical theory that the cosmos was constructed of the five regular polyhedrons, enclosed in a sphere, with a planet between each pair" (Ency. Brit., "Kepler").

Later, however, he helped initiate modern science. He was one of the earliest strong supporters of Copernicus's heliocentric theory, and he discovered the now-famous three principal laws of planetary motion: (1) the orbits of the planets are ellipses, not, as previously believed, circles; (2) planets move faster as they near the sun; and (3) a simple mathematical formula relates the planets' orbital periods to their distance from the sun.

Nevertheless, Kepler was still influenced by astrology, which he regarded as an adjunct to astronomy. In his famous book The Harmonies of the World (originally in Latin, published in 1619), he presented some of his most important revolutionary scientific ideas, yet he devoted the fifth section of the work to the old concept of the music of the spheres and colored his calculations with astrological and Christian interpretations.

Like the ancient Greeks, Kepler believed that the set of numbers that measured the relative lengths of harmonically tuned strings should also apply to celestial matters. However, the Greeks had thought that the pitches of the heavenly bodies were determined by the bodies' distances from, and therefore speeds relative to, the earth. Kepler, with his heliocentric focus derived from Copernicus, attempted, in The Harmonies of the World, to write out the music of the spheres, now including the earth, based on the idea that their pitches were determined by the bodies' distances from, and therefore speeds relative to, the sun.

In Kepler's system each planet had different speeds at different points in its elliptical orbit-slower speeds (and therefore lower pitches) when farther away from the sun, and faster speeds (and therefore higher pitches) when closer to the sun. Each planet, then, produced different pitches at different times-a sort of "melody."

Kepler calculated melodic outlines for the orbits of the six known planets (the five recognized since ancient times-Mercury, Venus, Mars, Jupiter, and Saturn-plus the earth), based primarily on each body's low pitch (at the aphelion) and high pitch (at the perihelion). He also developed a formula for the earth's moon.

The melodies, according to Kepler, "do not form articulately the intermediate positions, which you see here filled by notes, as they do the extremes, because they struggle from one extreme to the opposite not by leaps and intervals but by a continuum of tunings and actually traverse all the means (which are potentially infinite)-which cannot be expressed by me in any other way than by a continuous series of intermediate notes" (Kepler, 1039).

Kepler put three of his celestial melodies in the bass clef. From the first line, Saturn's melody was G, A, B, A, G. From the first line, Jupiter's melody was G, A, B-flat, A, G. From the fourth line, Mars's melody (Kepler labeled it "approximately") was F, G, A, B-flat, C, B-flat, A, G, F.

He put the four other melodies in the treble clef. From the second line, Earth's melody was G, A-flat, G. From the fourth space, Venus's melody was E, E, E. From middle C, Mercury's melody was C, D, E, F, G, A, B, C, D, E, C, G, E, C. From the second line, the moon's melody was G, A, B, C, B, A, G.

Kepler believed that the cosmic order revealed in the music of the spheres influenced human behavior. "You won't wonder any more," he wrote, "that a very excellent order of sounds or pitches in a musical system or scale has been set up by men, since you see that they are doing nothing else in this business except to play the apes of God the Creator and to act out, as it were, a certain drama of the ordination of the celestial movements" (Kepler, 1038).

Kepler drew a comparison between celestial music (simultaneous melodies produced by multiple celestial bodies) and the polyphonic music of his time. "It is no longer a surprise," he wrote, "that man, the ape of his Creator, should finally have discovered the art of singing polyphonically, which was unknown to the ancients, namely in order that he might play the everlastingness of all created time in some short part of an hour by means of an artistic concord of many voices and that he might to some extent taste the satisfaction of God the Workman with His own works, in that very sweet sense of delight elicited from this music which imitates God" (Kepler, 1048).

According to Kepler, "the movements of the heavens are nothing except a certain everlasting polyphony (intelligible, not audible)." Audible "voices or sounds do not exist in the heavens, on account of the very great tranquillity of movements." (Kepler, 1048-49)

Johannes Kepler was a transitional figure. "The last scientific astrologer," Carl Sagan wrote of Kepler, "was the first astrophysicist" (Sagan, 64).
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Encyclopaedia Britannica Ready Reference 2004 (CD-ROM).

Grout, Donald Jay, and Claude V. Palisca. A History of Western Music. 5th ed. New York: W.W. Norton, 1996.

Kepler, Johannes. The Harmonies of the World: V. Trans. Charles Glenn Wallis. Great Books of the Western World, vol. 16. Chicago: Encyclopaedia Britannica, 1952.

The New Grove Dictionary of Music and Musicians. 2nd ed. London: Macmillan, 2001.

Sagan, Carl. Cosmos. New York: Random House, 1980.