The Basran polymath, known in Latin as Alhazen, whose Book of Optics founded the modern understanding of vision and pioneered the experimental method.
Life
Born in Basra around 965 and working chiefly in Fatimid Cairo, Ibn al-Haytham wrote on optics, mathematics, and astronomy. His Kitab al-Manazir (Book of Optics) transformed the science of light and vision. Tradition holds he feigned madness to escape a rash promise to regulate the Nile's flooding for the caliph al-Hakim, spending years under house arrest, during which he wrote.
Struggles & Trials
The famous story of his life is his entanglement with the volatile Fatimid caliph al-Hakim: having boasted he could control the Nile and finding it impossible, he is said to have feigned insanity to avoid punishment, living confined until al-Hakim's death — and using the enforced solitude for his greatest work.
Teachings & Character
Ibn al-Haytham argued that vision results from light entering the eye, not rays leaving it, and insisted that claims be tested by controlled observation and experiment — an approach many historians credit as an early form of the scientific method. He prized doubt and verification over authority.
Campaigns & Conflicts
A scientist, Ibn al-Haytham had no military role; his "confinement" was the political peril of a scholar under an unpredictable ruler, not war.
Contested & Debated
Debates concern how far he anticipated the modern scientific method, and the reliability of the colorful biographical anecdotes (the Nile episode, the feigned madness). As with other medieval scientists, no authentic portrait survives, so no image is shown.
Legacy
Ibn al-Haytham's Book of Optics, translated into Latin, shaped European science from Roger Bacon to Kepler, and he is often called a father of optics and of the experimental method. His insistence on evidence over authority marks him as a pivotal figure in the history of science.