IN AN Istanbul manuscript collection of scientific and philosophical articles, there are several monographs by Thabit ibn Qurra, ninth-century mathematician and scientist. One of them is on the "Socratic proof" of the Pythagorean theorem.' This article is a letter written by the author to a friend who was somewhat disappointed with the "Socratic proof" of the Pythagorean theorem, as this proof deals with a special case only, namely, that of an isosceles right triangle, and he wished Thabit to… Expand