to be to rule the human race and gradually to educate it into self-rule; that they saw—these unknown devotees of science and truth—no other way of breaking down the barriers of Islam and setting free the spirits of men. A wild hypothesis! But in face of the real mystery no hypothesis can seem wild. [Sidenote: IKHWAN AS-SAFA] Closely allied with both al-Farabi and the Fatimids is the association known as the Sincere Brethren (_Ikhwan as-safa_). It existed at al-Basra in the middle of the fourth century of the Hijra during the breathing space which the free intellectual life enjoyed after the capture of Baghdad by the Buwayhids in 334. It will be remembered how that Persian dynasty was Shi‘ite by creed and how it, for the time, completely clipped the claws of the orthodox and Sunnite Abbasid Khalifas. The only thing, thereafter, which heretics and philosophers had to fear was the enmity of the populace, but that seems to have been great enough. The Hanbalite mob of Baghdad had grown to be a thing of terror. It was, then, an educational campaign on which this new philosophy had to enter. Their programme was by means of clubs, propagating themselves and spreading over the country from al-Basra and Baghdad, to 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 _Encyclopédie_. 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