(I just realized the spheres thing was vague - the spheres of which I speak are not the planets themselves, but either a) crystalline spheres in which the planets are embedded, like jewels set on the circumference of perfect glass balls. These spheres were nested in each other, and the friction of the spheres caused the harmony or "music of the spheres" (similar in concept to playing musical glasses - a wet finger rubbed on the rim of a glass making eerie, beautiful noise) or b) "virtual spheres" if you will - perfect circular motion, as mandated by the perfection of creation by a perfect and good god.