 Nicholas also recognizes in Book Two that the natural universe is characterized by change or motion; it is not static in time and space. But finite change and motion, ontologically speaking, are also matters of more and less and have no fixed maximum or minimum. This “ontological relativity” leads Cusanus to some remarkable conclusions about the earth and the physical universe, based not on empirical observation but on metaphysical grounds. The earth is not fixed in place at some given point because nothing is utterly at rest; nor can it be the exact physical center of the natural universe, even if it seems nearer the center than “the fixed stars.” Because the universe is in motion without fixed center or boundaries, none of the spheres of the Aristotelian and Ptolemaic world picture are exactly spherical. None of them has an exact center, and the “outermost sphere” is not a boundary. The universe is therefore “infinite,” in the sense of physically unbounded. Cusanus thus shifts the typical medieval picture of the created universe toward later views, but on ontological grounds.