To the ancient Greeks, it was natural to believe that the human body is a musical instrument based on proportional ratios. A person could be "high strung" just as the strings of a musical instument could be set too tight and shrill. These are some of the terms they used to describe types of tuning: Syntonos, "intense," Aneimenos, "relaxed," Charlaros, "slack," and Tonos, "in tune" which is still used as a medical term.

They also sought after the "tunings" of the planets, and really, there do seem to be some uncanny musical ratios at work. This is the "harmony of the spheres" that Kepler (1571-1650) was looking for. It was discovered by an amateur astronomer, J.D. Titius, in 1766.

Titius' discovery became the Titius-Bode Law when reintroduced by the Prussian Royal Astronomer Johann Elert Bode in 1772. It predicted the location of Uranus, discovered in 1781, with 97.8% accuracy. This caused a renewal of interest in the theory and the search for a planet between Mars and Jupiter began. The first Asteroid was discovered at a distance of about 2.8 Astronomical Units in 1801.

After many further discoveries, a series of marked gaps in the Asteroid belt emerged at 1/4, 2/7, 3/10, etc. of Jupiter's distance from the Sun. The asteroids are smashed to dust if they wander onto these nodal points. (The Kirkwood gaps in the rings of Saturn follow the same spacing.) Converted to decimal form the series is:

.25
.285714
.3
.333333
.375
.4
.428571
.454545
.5

If each term is then multiplied by 880, the result is close to the tuning of our "tempered" Major Scale, with the exception of the second and seventh notes and the extra "blue" note before the seventh note.

Where the fraction of Jupiter's distance is 2/3 and 1/1 there are, to the contrary, accumulations of matter. Interestingly, the asteroids out in Jupiter's orbit are swept along so as to remain always equidistant from the sun and Jupiter.

Titius-Bode Law Compared to Mean Distances

Planet	Bode	Miles (in Millions)	Accuracy
Mercury	0.4	36	x0.967
Venus	0.7	67	x1.029
Earth	1.0	93	x1.0
Mars	1.6	141	x0.947
Asteroids	2.8	204 to 297	-
Jupiter	5.2	484	x1.0
Saturn	10.0	888	x0.955
Uranus	19.6	1786	x0.98
Neptune	[NB]	2799	-
Pluto	38.8	3666	x1.016

NB. Nepture is an "extra" planet, which orbits far more elliptically than the others (right now it is more distant than Pluto). Bode's Law is regarded as a curiosity by most astronomers.