Born in Basra (now in Iraq), Alhazen was one of the most original scientists of his time. About a hundred works are attributed to him; the main one was translated into Latin in the 12th century and finally published in 1572 as Opticae thesaurus (The Treasury of Optics). This was widely studied and extremely influential. It was the first authoritative work to reject the curious Greek view that the eye sends out rays to the object looked at. Alhazen also made detailed measurements of angles of incidence and refraction. He studied spherical and parabolic mirrors, the camera obscura, and the role of the lens in vision. While the Greeks had had a good understanding of the formation of an image in a plane mirror, Alhazen tackled the much more difficult problem of the formation of images in spherical and parabolic mirrors and offered geometrical solutions. It is difficult to think of any other writer who had surpassed the Greeks in any branch of the exact sciences by the 14th let alone the 11th century. He was, however, unfortunate in his relationship with the deranged caliph al-Hakim. Having rashly claimed that he could regulate the flooding of the Nile, he was forced to simulate madness to escape execution until the caliph died in 1021.