heliocentricism

And as to Copernicus, he declared most expressly in his preface that he spoke of Heliocentricism as a pure hypothesis; the imagination of which was useful for the calculation of planetary orbits, but which “need not be true or even probable,” i.e., resting on any solid ground whatever.

I do not say for example that Heliocentricism is no truer than Geocentricism, but is only a simpler hypothesis.