"He was one of the most distinguished and prolific mathematicians in the medieval tradition of Arabic Islamic science. He became known in Europe in the thirteenth century as the author of the book on optics—the mathematical theory of vision. In his Kitâb al-Manâ zir (De aspectibus), if the eleventh-century he offered a new solution to the problem of vision, combining experimental investigations of the behavior of light with inventive geometrical proofs and constant forays into the psychology of visual perception — all systematically tied together to form a coherent alternative to the Euclidean and Ptolemaic theories of "visual rays" issuing from the eye."