Alhacen’s treatment of light and sight in the “De aspectibus” culminates with the analysis of refraction in book 7. Far briefer than his account of reflection, which occupies three books, Alhacen’s study of refraction follows essentially the same pattern of analysis, starting with various experiments designed to establish or confirm the governing principles of refraction empirically and proceeding to the application of those principles to specific cases according to the shape of the refracting surface. In many respects, in fact, reflection and refraction are side of the same coin according to Alhacen. Contents of this two-volume set: (1) Intro.: Alhacen’s Analysis of Refraction: An Overview; The Prolemaic Underpinnings of Alhacen’s Refraction Analysis; The Fate of Alhacen’s Refraction Analysis in the Latin West; Putting Alhacen in His Proper Place; (2) Manuscripts and Editing; (3) Latin Text; (4) English Translation. Glossary and Biblio. Illus.