 Grosseteste’s originality lay not in presenting a doctrine of first form and first matter.  Aristotle was standardly understood to propound a notion of first or prime matter, and the notion of a first form may be found in texts of Neoplatonic inspiration, such as the Fons vitae of Avicebron (see McEvoy 1982, 158–162).  What appears to be original, however, is Grosseteste’s identification of first form with light (lux). On Light opens with an argument for this identification. Grosseteste asserts that first form and first matter are in themselves simple substances. Yet first form, corporeity, necessarily results in the extension of matter into three dimensions, thereby yielding a quantified body. A simple form without dimension could only have this effect, however, if it instantaneously multiplied and diffused itself in all directions, thereby extending matter along with its diffusion of itself. But these are characteristic features of light, for light is essentially self-multiplicative and self-diffusive, a sphere of light being instantaneously generated from a point of light. Thus, Grosseteste concludes that light is in fact the first form.