" Magnetism also was an influence felt at a distance, and in a stunning anticipation of the idea of universal gravitation, Kepler suggested that the underlying cause was akin to magnetism: My aim in this is to show that the celestial machine is to be likened not to a divine organism but rather to a clockwork …, insofar as nearly all the manifold movements are carried out by means of a single, quite simple magnetic force, as in the case of a clockwork [where] all motions [are caused] by a simple weight. "

― Carl Sagan , Cosmos