text:  We can conceive the sun or moon falling for although we never saw them fall nor ever perhaps imagined them falling we have seen so many other things fall that we have innumerable familiar analogies to assist the conception; which after all we should probably have some difficulty in framing were we not well accustomed to see the sun and moon move (or appear to move ) so that we are only called upon to conceive a slight change in the direction of motion a circumstance familiar to our experience