 Bacon’s treatise De multiplicatione specierum, his major later work on physics, written before 1267, is closely related to the study of light, vision, and perception in the Perspectiva. David C. Lindberg (DMP, Introduction) has noted that Bacon takes Grosseteste’s physics of light, a development of Al-Kindi’s universal radiation of force, out of its metaphysical background and develops a universal doctrine of physical causation.