The belief in the harmony of the spheres came through Plato (c. 430- 330 BCE), and from earlier sources, especially the Pythagoreans (c. 570 BCE on).
The motions of the planets and stars were believed to be based on circles and spheres, and on ratios that were also known to be associated with musical intevals.
One facet of the tradition was mythical and metaphysical, the earliest full account being in Plato's Republic. The other facet was quantitative and proto-scientific, and is represented in Plato's Timeaus.This facet linked the arithmetical ratios of musical intervals to celestial motions, through perfect circles. This principle became the basis of Ptolemy's model of the universe, that dominated Western astronomy for over a millennium until a more accurate description based on Newton's laws of motion replaced it.