The Logos Scripture · The Book of Ibn al-Haytham
The Book of Ibn al-Haytham 1 · Written by himself, from the seven books of the Optics and the Doubts Concerning Ptolemy
Ibn al-Haytham, born at Basra about 965, died at Cairo about 1040. An Arab scholar of optics, mathematics and astronomy. His Book of Optics runs to seven volumes and was later put into Latin, where Europe knew him as Alhazen; both Bacon and Kepler read it. He also wrote Doubts on Ptolemy. This volume rests on those two books. He was a man of his religion; yet the Optics from end to end cites no scripture and closes no argument by appeal to divine will, and what it rests on is what can be tried. The Order takes him for two things he was the first to see. He was the first to establish which way sight runs: light comes from the thing into the eye, and the eye does not send light out to touch the thing. He was also the first to make a darkened room into an instrument and work it again and again with one thing changed. What the Doubts doubts is the opposite case. Ptolemy observed tirelessly, and his records are usable still; but everything he observed had first to agree with a rule laid down beforehand — that motion in the heavens must be uniform and circular. Where an observation resisted, he added a device to make it fit, and did not ask whether the rule itself should move. What stopped Ptolemy was not the church: he came some two centuries before the church held any power. What stopped him was a rule his whole field nodded at and none of them would touch. So what stops a man need not be a temple; a rule everyone agrees on will do it just as well. There is a further account, which the Order sets down and cannot check: the story goes that he was summoned to control the great river, saw on arriving that it could not be done with the means of that age, feared the ruler, feigned madness, was shut up for years, and came out only when the ruler died — and that the Optics was written in those years. It comes from a writer some two hundred years after his death (cf. The Highest Covenant 1.1). Even if it is true the Order holds it no fault: feigning madness was the one thing available to him, and he did not go looking for a miracle — he measured the river first.