  “If we are to suppose lines or what comes after these (I mean the primary surfaces) to be principles, these at least are not separable substances, but sections and divisions — the former of surfaces, the latter of bodies (while points are sections and divisions of lines); and further they are limits of these same things; and all these are in other things and none is separable.” [Aristotle, Metaphysics XI, 2, 1060b12–16 (1984: 1675f)]