Abu Ali ibn Al-Haytham (965–1040)

The Arabic scientist Al-Haytham is said to have saved his life by feigning madness. Realizing that the irrigation problem he had been ordered to solve was impossible, Al-Haytham avoided the wrath of the Caliph by his pretended insanity.

Al-Haytham was born in Basra, Iraq, but lived most of his life in Cairo where he wrote most of his books. Al-Haytham's most important book, Kitab al-manazir, (Book of Optics) was written around 1038, shortly before his death in 1040.

This book remained unknown for a long time. However around 1300 it began to be spread through the Arabic world and then to Europe, where Al-Haytham's ideas laid the foundations for the revival of optics as a modern science by Roger Bacon, Johannes Kepler and others.

Al-Haytham's book corrected many errors of earlier scientists, and included descriptions of simple experiments with pinhole cameras, and anatomical studies of the eye.

Al-Haytham also described the role played by the brain in interpreting what is seen by the eyes. This allowed Al-Haytham to account for optical illusions, including the Moon illusion, where the Moon appears larger on the horizon than it does when it is overhead.