An example of a historical scientific notion
"If one asked Copernicus why the earth and the heavenly bodies moved, he would answer: Because they were spherical or because they were attached to spherical orbs. Put a sphere anywhere in space and it would naturally revolve – it would turn without needing anybody to turn it because it was the very nature of the sphere to rotate in this way."
Herbert Butterfield (1957) The Origins of Modern Science 1300-1800 (New Edition: Revised and enlarged). G. Bell and Sons Ltd., London.
Nicolaus Copernicus is rightly remembered a major figure in the history of science because of his championing of the heliocentric model (planets moving around the sun) as opposed to the widely accepted geocentric model (the earth is at the centre of the universe, and everything else rotates around it). However, in many ways his idea reflected ancient and medieval ideas (such as here, that the movement of the heavenly bodies is 'natural' and does not needs to be explained in terms of forces) that are now recognised to be alternative conceptions. (The major shift in thinking associated with, and starting with, Copernicus was continued and developed in parts by others such as Kepler, Galileo and Newton).
