 If a single leitmotif runs through Grosseteste’s works, it is that of light.  The notion of light occupies a prominent place in Grosseteste’s commentaries on the Bible, in his account of sense perception and the relation of body and soul, in his illuminationist theory of knowledge, in his account of the origin and nature of the physical world, and, of course, in his writings on optics.  Just how tightly associated Grosseteste took the notions of light employed in such different contexts to be is unclear. From a philosophical point of view, which will be the focus here, undoubtedly his use of the notion of light in his account of the basic structure and origin of the physical universe is of fundamental importance and the greatest originality.