Al-Hasan Ibn al-Haytham was born in 965 CE (354 AH) in Basra, Iraq, and received his early education there before moving to Baghdad, then the center of scientific civilization in the Islamic world. He studied mathematics, astronomy, medicine, and philosophy, later moving to Cairo under the Fatimid Caliphate, where he spent most of his scientific career and worked for a time at the House of Wisdom, one of the era's leading centers of research.
Before Ibn al-Haytham, two competing theories explained vision: one held that the eye emits rays that touch objects to see them, while the other attributed vision to images emanating from objects themselves. In his most famous work, the «Book of Optics» (Kitab al-Manazir), Ibn al-Haytham proved through careful experiments that vision occurs when light reflected from objects enters the eye, not the reverse, establishing the correct foundation of modern optics. He also studied the refraction and reflection of light, the nature of the rainbow, the anatomical structure of the eye, and used the camera obscura in his experiments to demonstrate that light travels in straight lines.
Scientific Legacy
Ibn al-Haytham is regarded as one of the earliest scientists to apply a systematic experimental method based on observation, hypothesis, experimentation, and repeated verification, rather than relying solely on the authority of earlier scholars — leading many historians to consider him a pioneer of the modern scientific method. His «Book of Optics» was translated into Latin as De Aspectibus and circulated widely in medieval Europe, profoundly influencing later scholars such as Roger Bacon and Johannes Kepler. He died in Cairo in 1040 CE, leaving a scientific legacy that spanned centuries.
