Round and round

“Have you ever observed a complete revolution of a millstone? Each point in the extreme circumference of the stone describes a large circle in the same time in which a point nearer the center describes a small circle; the velocity of the outside circle is therefore greater than that of the inner circle. You cannot say that the motion of the latter was interrupted by more moments of rest; for the whole moving body, i.e., the millstone, is one coherent body.” They reply, “During the circular motion, the parts of the millstone separate from each other, and the moments of rest interrupting the motion of the portions nearer the center are more than those which interrupt the motion of the outer portions.” We ask again, “How is it that the millstone, which we perceive as one body, and which cannot be easily broken, even with a hammer, resolves into its atoms when it moves, and becomes again one coherent body, returning to its previous state as soon as it come to rest, while no one is able to notice the breaking up of the stone?” Again their reply is based on the twelfth proposition, which is to the effect that the perception of the senses cannot be trusted, and thus only the evidence of the intellect is admissible.

Moses Maimonides, The guide for the perplexed, trans. M. Friedlaender (New York: Pardes, 1946), pg. 122; qtd. in Max Jammer, Concepts of Space (Cambridge: Harvard UP, 1954), pg. 66.