The Copernican Harmony

Abstract

The Copernican revolution is described by Copernicus in his Letter to the Pope that opens his book:

Thus assuming motions, which in my work I ascribe to the earth, by long and frequent considerations I have at last discovered that if the motions of the rest of the planets be brought into relation with the circulation of the earth and be reckoned in proportion to the circles of each planet, not only do their phenomena presently ensue, but the order and magnitudes of all the stars and spheres, nay, the heavens themselves, become so bound together, that nothing in any part thereof could be moved from its place without producing confusion of all the other parts of the universe as a whole.

(De Rev2:5) He says that (a) discovered a way of turning existing astronomy into a harmonic system, (b) this harmony consists in a rigidity towards changes in some parameters in the system, (c) these parameters are the “order and magnitude of the spheres,” (d) and lastly, by implication, all this was lacking in the existing astronomy. It is therefore, the logical structure of his theory, which makes it impossible to correct the “order and magnitude” of a single “sphere”, without a complete rearrangement of the whole system. Copernicus says, in the above passage, that such a rigidity of the theory results from transferring certain motions of the planets to the earth.