Robert Grosseteste and his Treatise on Lines, Angles and Figures of the Propagation of Light

Robert Grosseteste, an English philosopher and scientist, Bishop of Lincoln, is considered as the founder of the scientific thought in medieval Oxford. During the beginning of the XIII century he wrote several scientific papers concerning light and its propagation, where he based the description of some phenomena on the use of geometry. Here we will translate and discuss one of his scientific treatises concerning light, which is entitled De Lineis, Angulis et Figuris, seu Fractionibus et Reflexionibus Radiorum. Since to Grosseteste, the propagation of light had the main role in the creation of the world, the use of its geometry becomes a method to solve the complexity of the physical world. However, besides the use of geometry, we will find in this interesting text the description of some phenomena concerning the intensity of reflected and refracted light, which seems well-posed, even when compared with the modern Fresnel theor