Ibræhîm ibn Sinæn ibn Thæbit ibn Qurra was born in Baghdad in 296/909, where he died following an illness 37 years later, in 335/946.1 He was an ‘heir’ in the strict sense, but in fact, as we shall see, in all senses of the word, for he was also a mathematician of genius: all the signs forecast great works. Despite the shortness of his life, Ibræhîm ibn Sinæn was by no means disappointed.