Islam—the Zaydites were accused of rationalism. Their founder, Zayd, the grandson of al-Husayn, had studied under the great Mu‘tazilite, Wasil ibn Ata, of whom much more hereafter. [Sidenote: IMAMITES] But if the Zaydites were lax both in their theology and in their theory of the state, that cannot be said of another division of the Shi‘ites, called the Imamites on account of the stress which they laid on the doctrine of the person of the Imam. For them the Imam of the time was explicitly and personally indicated, Ali by Muhammad and each of the others in turn by his predecessor. But it was hard to reconcile with this _a priori_ position that an Imam must have been indicated, the fact that there was no agreement as to the Imam who had been indicated. Down all possible lines of descent the sacred succession was traced until, of the seventy-two sects that the Prophet had foretold for his people, seventy, at least, were occupied by the Imamites alone. Further, the number of Hidden Imams was constantly running up; with every generation, Alids found it convenient to withdraw into retirement and have reports given out of their own deaths. Then two sects would come into existence—one which stopped at the Alid in question, and said that he was being kept in concealment by God to be brought back at His pleasure; and another which passed the Imamship on to the next generation. Out of this chaos two sects, adhering to two series of Imams, stand clear through their historical importance. The one is that of the Twelvers (_Ithna‘ashariya_); theirs is the official creed of modern Persia. About A.H. 260 a certain Muhammad ibn al-Hasan, twelfth in descent from Ali, vanished in the way just described. The sect which looked for his return increased and flourished until, at length, with the conquest of Persia in A.H. 907 (A.D. 1502) by the Safawids—a family of Alid descent which joined arms to sainthood—Persia became Shi‘ite, and the series of the Shahs of Persia was begun. The position of the Shah is therefore essentially different from that of the Khalifa of the Sunnites. The Khalifa is the successor of Muhammad, with a dignity and authority which inheres in himself; he is both king and pontiff; the Shah is a mere _locum tenens_, and reigns only until God is pleased to restore to men the true Imam. That Imam is still in existence, though hidden from human eyes. The Shah, therefore, has strictly no legal authority; he is only a guardian of the public order. True legal authority lies, rather, with the learned doctors of religion and law. As a consequence of this, the Shi‘ites still have _Mujtahids_, divines and legists who have a right to form opinions of their own, can expound the original sources at first hand, and can claim the unquestioning assent of their disciples. Such men have not existed among the Sunnites since the middle of the third century of the Hijra; from that time on all Sunnites have been compelled to