  (i) The theoretical sciences include prominently what Aristotle calls first philosophy, or metaphysics as we now call it, but also mathematics, and physics, or natural philosophy.  Physics studies the natural universe as a whole, and tends in Aristotle’s hands to concentrate on conceptual puzzles pertaining to nature rather than on empirical research; but it reaches further, so that it includes also a theory of causal explanation and finally even a proof of an unmoved mover thought to be the first and final cause of all motion. Many of the puzzles of primary concern to Aristotle have proven perennially attractive to philosophers, mathematicians, and theoretically inclined natural scientists. They include, as a small sample, Zeno’s paradoxes of motion, puzzles about time, the nature of place, and difficulties encountered in thought about the infinite. 