The notion of light occupies a relevant place in Grosseteste’s philosophy and theology, as the fundamental monographs by McEvoy (1982, 2000) clearly show. After his early scientific interests in astrological causality,
Grosseteste elaborated his own original doctrine (partly influenced by Avicenna and Avicebron) in his most famous short work, De luce, arguing that light (lux) is “corporeity,” that is, the first common form which gives dimensionality to the a-dimensional prime matter. Grosseteste builds his own cosmology according to this ontological principle, asserting that, at the beginning of time, first light and first matter multiplied infinitely producing the sphere of the universe, which is structured by light’s replicability (replicabilitas) into finite-sized bodies of infinite ‘‘light-atoms.’’ Therefore light, according to the Aristotelian concept of entelechy, produces the transition from physical potentiality to actuality (Gieben 1966). In addition to light, natural bodies include other substantial forms, except the outermost heavenly sphere, which is the simplest body. It emits a luminosity (lumen) which operates over the lower bodies as an active force, entering within the elements to cause movement, sound, colours, and every natural change, including sense perception. This is the so-called theory of light-incorporation (Panti 1999). Light also explains some features of the Aristotelian cosmos developed in the commentary on Physics. Basically, Aristotle’s three principles of form, privation, and the underlying subject, are interpreted as light, the impurity of light in things, and first matter (Lewis 2005).
to its infinite and indivisible constituents - the light-atoms - every physical body is ‘‘measured’’ through an original mathematics of infinities, introduced in De luce, which aims to connect Aristotelian physics and Platonic cosmology. Grosseteste’s commentary on Physics further develops such an idea, asserting that the true measure of bodies is provided by their different-sized infinities, which only God can count in definite mathematical numbers (Lewis 2005). Besides, the very existence of physical bodies presupposes a Creator of infinite power, for the passing from nothing to being (i. e., from a-dimensionality to dimensionality) requires an infinite efficient power. But in his theological works, such as De unica forma and De statu causarum, and in the late commentary on Pseudo-Dionysius, Grosseteste develops the idea that the creature’s being also needs to be constantly supported by God, who gives it its own form by modeling it to himself, as a vessel shapes water by adhering to it (Gieben in O’Carrol 2003). Grosseteste, following Augustine, describes divine creation as the infusion of the first form, which is now considered to be the simple and separate exemplar in God’s mind, by virtue of which a thing exists. In his theological works, Grosseteste also uses his metaphysics of light to explain the heavenly movements, associated with angelic operations (McEvoy 1982, part 2), although in his earlier De motu supercelestium he follows the Averroistic doctrine that the heavenly movements are produced by a purely intellectual power (Panti 2001).
In conclusion, Grosseteste develops two complementary ideas on natural being: as a physical body, everything is ‘‘made of’’ atoms of light/form and matter; as a creature, everything is ‘‘shaped’’ from divine light/form, which is its external and perfect exemplar.
World History
