Translation and discussion of the De Iride, a treatise on optics by Robert Grosseteste

Here I am proposing a translation and discussion of the De Iride, one of the short scientific treatise written by Robert Grosseteste. In the first part of his Latin text we find reflection and refraction of light, described in a geometrical optics. In the second part, Grosseteste is discussing the rainbow and how the colors are created.