The Gradual Acceptance of the Copernican Theory of the Universe is a classic science study that does not belong in the field of astronomy, but in that of the history of thought; for it is an endeavor to trace the changes in people's beliefs and conceptions in regard to the universe as these were wrought by the dissolution of superstition resulting from the scientific and rationalist movements. The opening chapter is intended to do no more than to review briefly the astronomical theories up to the age of Copernicus, in order to provide a background for the better comprehension of the work of Copernicus and its effects.