This is Cemil Akdogan's doctoral dissertation in which he examines Albert the Great's treatment of visual theory, and analyses his Muslim sources. Thus it provides crucial information on the legacy of Muslim thinkers as Avicenna, Averroes and Al-Kindi's names as well as others are all mentionaed. The fact that Albers borrowed and cited key studies from the Muslim thinkers also shed light on the interaction and movement of knowledge between western and Islamic academia.