Robert Grosseteste's De iride and its Addendum in the Vatican Manuscript Barb. Lat. 165: Transmission, Reception, Meaning

This study examines Grosseteste’s treatise De iride – which was known to later medieval scholars such as Roger Bacon from three perspectives: first, its manuscript transmission; second, the later readers’ response to it; and third, its place in Grosseteste’s general colour theory and its relationship with his De colore. For later readers' response, the paper examines in detail the addendum to De iride transmitted in BAV Barb. lat. 165, which presents Bacon’s two main criticisms of De iride, even though it also proposes something akin to Grosseteste’s theory of colour as light incorporated into a transparent medium, an idea that is not followed by Bacon. Consequently, the addendum can be seen as either an intermediate step between the solutions of the two English masters, or, perhaps more likely, an attempt to combine the best of both theories.