Reflection, Refraction and Transmission of Light in Grosseteste's Physics

Robert Grosseteste was one of the most prominent thinkers of the Thirteenth Century. Philosopher and scientist, he was Bishop of Lincoln from 1235 to 1253. He was heavily influenced by Augustine, whose thought permeates his writings and his Neoplatonic outlook. Grosseteste made also extensive use of the thought of Aristotle, Avicenna and Averroes in his science of Nature. In the scientific treatises written by Grosseteste, mainly concerning physics, we can find some interesting experiments and phenomena about optics, acoustic, heat and phase transitions. Here we discuss how, in one of his treatises of optics, the De Iride, Grosseteste is discussing reflection, refraction and transmission of light.