 In discussing sense data, Moore introduced some facts that illustrate the relativity of perception, using coins (1913–14: 371–372). With U.S. coins, a penny is physically smaller than a quarter and both are round. Moore and other observers report that when looking at the coins from a position other than directly above them, they appear more or less elliptical, becoming thin rectangles when seen edge-on. Further, the quarter, seen at a sufficiently greater distance than the penny, appears smaller than it. Moore wanted to account for these purported facts that exhibit perceptual relativity, while preserving the common-sense beliefs that we really do, on some occasions, see coins; that the coins really are round; that they have an inside and a lower side, even though these aren’t presently seen; that the quarter is really larger than the penny; and that the coins exist when we aren’t looking at them.