Optical Problems and Light Terminology in The Writings of 'Ali Qushji (D. 879/1474)

Abstract

This study seeks to provide a historical perspective on optical problems by analyzing issues related to optics addressed by Ali Qushji in his works Shar al-Tajrid and Taliqat ala Mabaith al-Aghalit al-issiya min Shar al-Mawaqif and examining his use of different optical terms such as ad-aw (), an-nur (), and ash-shua (). In his work Shar al-Tajrid, Ali Qushji offers a detailed exploration of the faculty of sight, drawing insights from mathematicians and natural philosophers on the nature of visual perception. He examines the formation of images in mirrors, delves into the concept of aw (light), and discusses its significance in visual and color perception, as well as the limitations of conceiving aw as an object. He concludes by addressing the challenges associated with seeing in the dark. In his treatise Taliqat ala Mabaith 'al-Agalit al-issiya min Shar al-Mawaqif, Ali Qushji further investigates topics such as the relative motion of an observer on a ship, methods for determining the size of objects reflected in mirrors using similar triangles, and the occurrence of different colors. Throughout his writings, he intricately weaves optical problems with broader issues in natural philosophy, discussing theories of motion and the physiology of the eye while bolstering his arguments with geometric representations. Additionally, he utilizes various terms for light when addressing light phenomena in both his Shar al-Tajrid and Taliqat.