The greatest product in Asia of the ferment of thought produced by the general study of the Aristotelian and neo-Platonic philosophies appears in _Abu `Ali al-Husayn b. `Abdullah b. Sina_ (d. 428 = A.D. 1027), commonly known as Ibn Sina, which is Latinized as Avicenna. His life is known to us from an autobiography completed by his pupil, Abu `Ubayd al-Juzjani, from his master’s recollections. We learn that his father was governor of Kharmayta, but, after his son’s birth, he returned to Bukhara, which had been the original home of his family, and it was there that Ibn Sina received his education. During his youth some Isma`ilian missionaries arrived from Egypt, and his father became one of their converts. From them the son learned Greek, philosophy, geometry, and arithmetic. This helps to remind us how the whole Isma`ilian propaganda was associated with Hellenistic learning. It is sometimes stated that the Egypt of the Fatimite age was isolated from the intellectual life of Islam at large: but this is hardly accurate; from first to last the whole of the Isma`ilian movement was connected with the intellectual revival due to the reproduction of Greek philosophy in Arabic form, less so, of course, when the Isma`ilian converts were drawn from the illiterate classes, as was the case with the Qarmatians, and when the attention of the members was engrossed with political ambitions, as was the case with the Fatimids whilst they were building up their power in Africa before the invasion of Egypt. But even under the most unfavourable conditions it seems that the _da`is_ or missionaries regarded the spread of science and philosophy as a leading part of their duties, quite as much so as the preaching of the `Alid claims of the Fatimite Khalif. Learning Greek and Greek philosophy from these missionaries Ibn Sina made rapid progress, and then turned to the study of jurisprudence and mystic theology. Jurisprudence, that is to say, the canon law based on one of the orthodox systems laid down by Abu Hanifa and the other recognised jurists, or by their Shi`ite rivals, has always been the backbone of Islamic scholarship, and was thus parallel with the study of canon law in mediæval Europe: in each case it turned men’s attention to the development of the social structure towards an ideal, and this had an educative influence of the highest value. We, holding very different principles, may be tempted to under-estimate this influence, but it is worth noting that, whilst our aims are opportunist in character, the canonist of Islam or of Christendom had a more definitely constructed ideal, with a more complete and scientific finality, which, in so far as it was an ideal, was an uplifting power. In Muslim lands the canonists were the one power which had the courage and ability to resist the caprices of an autocratic government, and to compel even the most arbitrary princes to submit to principles which, however narrow