  Paul Woodruff has defined hylomorphism as “the doctrine, first taught by Aristotle, that concrete substance consists of forms in matter (hyle)” (Audi [1999], p. 408). One might therefore expect universal hylomorphism to be the doctrine that all substances consist of forms in matter. But in fact the medieval theory of universal hylomorphism maintained something slightly weaker than that; it held that all substances except God were composed of matter and form, whereas God is entirely immaterial.