Ibn al-Haytham

Born in Basra around 965, Ibn al-Haytham spent his working life in Fatimid Cairo, earning his keep writing treatises and tutoring nobles. Between 1011 and 1021 he completed the Kitāb al-Manāẓir, a systematic investigation of reflection, refraction, and image formation that survived in Latin and became a cornerstone text — Kepler, Galileo, Descartes, and Huygens all cited him centuries later. He was first to describe spherical aberration, the horopter, and color constancy, first to argue that vision happens in the brain and is shaped by experience, and first to insist that hypotheses be tested…