How Islam changed medicine

Editor—Majeed elaborated on the role of Muslim physicians and scholars in modern medicine and mentioned the contributions of various Arab doctors during the middle ages.¹ Here is a contribution to optics.

Ibn al-Haytham (known to the West as Alhacen or Alhazen) lived from 965 to about 1040. He was a distinguished mathematician, astronomer, and philosopher of his time, and he became known in Europe as the author of a monumental book on optics, Kitab al-Manazir (translated into Latin as De Perspectiva or De Aspectibus² and partly translated into English as The Optics³). Ibn al-Haytham described in detail the various parts of the eye and introduced the idea that objects are seen by rays of light emanating from the objects and not the eyes, as was popularly believed at the time, following Ptolemy's and Euclid's theory of vision. “Sight perceives the light and colour existing on the surface of the contemplated object... Vision perceives necessarily all the objects through supposed straight lines that spread themselves between the object and the central point of the sight.”⁴

He also discovered the laws of refraction and carried experiments on the passage of light through various media and the dispersion of light into its constituent colours. He wrote about optical illusions, spherical and parabolic mirrors, shadows, and eclipses. Because of his contribution in optics, many regard him as “the father of optics.”⁵