Grosseteste describes this as the process in which the mind is stimulated on the occasion of sense experience to seek and find its own light—to turn from corruptible corporeal objects to intelligible things. The mind moves out of the darkness it is in to find a trace of its light, which stands to it as the sun stands to the eyes in bodily vision. As he puts it in discussing certainty, “there is a spiritual light shed on intelligible things and the mind’s eye, and this light is related to the inner eye and intelligible things in the way the bodily sun is related to bodily eyes and visible bodily things” (Rossi 1981, 240–241). Understanding (intellectus) and demonstrative knowledge are “like the vision of healthy eyes through the medium of pure air with clear light spread over the colored object…Understanding and demonstrative knowledge apprehend things in the purity of their essence, as they are in themselves” (Rossi 1981, 279–280).