reach all educated people and introduce among them gradually a complete change in their religious and scientific ideas. Their teaching was the same combination of neo-Platonic speculation and mysticism with Aristotelian natural science, wrapped in Mu'tazilite theology, that we have already known. Only there was added to it a Pythagorean reverence for numbers, and everything, besides, was treated in an eminently superficial and popularized manner. Our knowledge of the Fraternity and its objects is based on its publication, "The Epistles of the Sincere Brethren" (Rasa'il ikhwan as-safa) and upon scanty historical notices. The Epistles are fifty or fifty-one in number and cover the field of human knowledge as then conceived. They form, in fact, an Arabic Encyclopedie. The founders of the Fraternity, and authors, presumably, of the Epistles, were at most ten. We have no certain knowledge that the Fraternity ever took even its first step and spread to Baghdad. Beyond that almost certainly the development did not pass. The division of members into four—learners, teachers, guides, and drawers near to God in supernatural vision—and the plan of regular meetings of each circle for study and mutual edification remained in its paper form. The society was half a secret one and lacked, apparently, vitality and energy. There was among its founders no man of weight and character. So it passed away and has left only these Epistles which have come down to us in numerous MSS., showing how eagerly they have been read and copied and how much influence they at least must have exercised. That influence must

have been very mixed. It was, it is true, for intellectual life, yet it carried with it in a still higher degree the defects we have already noticed in al-Farabi. To them must be added the most simple skimming of all real philosophical problems and a treatment of nature and natural science which had lost all connection with facts.

It has been suggested, and the suggestion seems luminous and fertile, that this Fraternity was simply a part of the great Fatimid propaganda which, as we know, honey-combed the ground everywhere under the Sunnite Abbasids. Descriptions which have reached us of the methods followed by the leaders of the Fraternity agree exactly with those of the missionaries of the Isma'ilians. They raised difficulties and suggested serious questionings; hinted at possible answers but did not give them; referred to a source where all questions would be answered. Again, their catch-words and fixed phrases are the same as those afterward used by the Assassins, and we have traces of these Epistles forming a part of the sacred library of the Assassins. It is to be remembered that the Assassins were not simply robber bands who struck terror by their methods. Both the western and the eastern branches were devoted to science, and it may be that in their mountain fortresses there was the most absolute devotion to true learning that then existed. When the Mongols captured Alamut, they found it rich in MSS. and in instruments and apparatus of every kind. It is then possible that the elevated eclecticism of the Ikhwan as-safa was the real doctrine of the Fatimids, the