The latter educated two pupils during his office (950-980), and they were afterwards recognized as authorities. These were his son Chananel and a native, Jacob ben Nissim Ibn-Shahin. The physician and favorite of the first two Caliphs, Isaac Israeli, had sown the seeds of Jewish science, which was developed by a pupil of his who likewise obtained court favor. This pupil, Abusahal Dunash ben Tamim (900-960), the head of Jewish science in the Fatimide dominions, was physician to the third Fatimide Caliph, Ishmael Almansur Ibnul' Kaim, perhaps also to his father. Dunash was held in such favor by this ruler that he dedicated to him one of his works on astronomy. Dunash ben Tamim came from Irak, perfected himself in his youth under Isaac Israeli in Kairuan, learning from him medicine, languages, and metaphysics. Dunash ben Tamim was accomplished in the whole circle of sciences then known, and wrote books on medicine, astronomy and mathematics. He also classified the sciences; in his opinion, mathematics, astronomy, and music rank lowest; next come physics and medicine; highest of all is metaphysics, the knowledge of God and the soul. The Arabs thought so highly of Dunash that they said that he had became a convert to Islam, doubtless in order that they might count him amongst their own, but he certainly remained faithful to Judaism to the end of his life. He corresponded with the Jewish statesman Chasdaï, for whom he composed an astronomical work on the Jewish calendar. Meanwhile, though Dunash was not a genius, he was able to give the community of Kairuan, and through them to a wider circle, a more scientific understanding of Judaism. The Fatimide Caliphate, however, was not calculated to become a seat of culture for the Jews. The fanatic Fatimide dynasty--raised to power through an enthusiastic missionary, who saw in the Caliph of the house of Ali a kind of embodied divinity, and founded by a deluded deceiver who considered himself the true Imam and Mahdi (priest)--could not logically tolerate Judaism. The successors of the first Fatimide Caliph used, just as the successors of the first Christian Emperor had done, the sword as the means of spreading religion. Soon there came to the throne a Fatimide who repaired what his ancestors had in their indulgence neglected, and preached the doctrines of the divine Imamate with bloody fanaticism. In such surroundings Judaism could not flourish; it required a more favorable situation.