Most of the Shi`ites regard the third Imam, al-Husayn as being succeeded by his son `Ali Zayn. Al-Husayn, like al-Hasan, was not only the son of `Ali, but also of the Prophet’s daughter, Fatima. In al-Husayn’s case moreover there was another heritage which ultimately proved more important than descent from either `Ali or Fatima: he was generally supposed to have married the daughter of the last of the Persian kings, the “mother of the Imams,” and this traditional marriage with the Persian princess,--its historical evidence is very dubious--has been regarded by the Persian Shi`ites as the most important factor in the Imamate, although this, of course, has nothing whatever to do with the religion of Islam. That so great weight could be attached to such a consideration serves to show how really foreign and non-Muslim a thing the Shi`a is. `Ali Zayn had two sons, Zayd and Muhammad al-Bakir. Of these Zayd was a pupil of Wasil b. `Ata and associated with the Mu`tazilite movement: he is generally regarded as a rationalist. Indeed, as we shall now see frequently, the heretical Shi`ite party was very generally mixed up with free thought and frequently shows adherence to Greek philosophy: it seems as though its inspiring spirit was hostility towards orthodox Islam, and a readiness to ally itself with anything which tended to criticize unfavourably the orthodox doctrines. Zayd had a body of followers who established themselves in North Persia where they held their own for some time, and a branch of their party still exists in South Arabia, still suspected of rationalist proclivities. Most of the Shi`ites, however, recognised Muhammad al-Bakir as the fifth Imam, and Ja`far as-Sadiq as the sixth. This latter also was a devoted follower of the “new learning,” that is to say, of Hellenistic philosophy, and is generally regarded as the founder, or at least the chief exponent, of what are known as _batinite_ views, that is to say the allegorical interpretation of the Qur´an, so that revelation is made to mean, not the literal statement, but an inner meaning, and this inner meaning generally shows a strong influence of Hellenistic philosophy. It is only the divinely directed Imam who can expound the true meaning of the Qur´an which remains a sealed book to the uninitiated. Ja`far was, it would appear, the first of the `Alids who openly asserted that he was a divine incarnation as well as an inspired teacher: his predecessors had done no more than acquiesce in such claims when made by their followers, and very often had repudiated them.