The position of the patriarch remained hereditary in the house of Judah Hanasi, until the office was abolished by the decree of Emperor Theodosius II (about 420). The successors of Judah Hanasi were Gamaliel III, Judah II, Gamaliel IV, Judah III, Hillel II, Gamaliel V, Judah IV, and Gamaliel VI. These patriarchs, however, were not prominent as scholars, and while they were the religious heads of the community, the prerogatives of the president of the school of Tiberias were transferred to a scholar of prominence. Thus Judah Hanasi himself appointed his son Gamaliel as his successor before his death, but Rabbi Hanina was named as president of the school. It is probable that the head of this school presided also over the court sessions, so that he was the Ab Beth Din; the Nasi, who formerly exercised these prerogatives, was the representative of the Jewish community only through the dignity of his office. Prominent among the disciples of Hanina were Johanan bar Nappaha, Simeon ben Lakish, and Eleazar bar Padath (250-280). Even at this period the Mishnah was already considered revealed law, which the teacher could only explain, but not alter. We therefore very often find their names in the Talmud at the head of discussions of a passage in the Mishnah. They introduced the period of the Palestinian Amoraim, as the scholars following the era of the Mishnah are called in contradistinction to the teachers of the Mishnah, known as Tanaim. To the school of Johanan belong all prominent Palestinian rabbis of the succeeding generation. Prominent among them is Abbahu of Cæsarea. He is known not merely as an expounder of the law but as a controversialist against Christianity. Tiberias continued to be the center of Jewish spiritual life, and quite a number of young scholars from Babylonia came there to finish their studies; some of them remained in Palestine. Of the teachers of the fourth century, little more than their names is known. Prominently mentioned, however, is Rabbi Jose, to whom is ascribed the final redaction of the Palestinian Talmud (350). At about this time Hillel II gave up the only tangible privilege of the Nasi, the announcement of the calendar. Instead of announcing the leap-year whenever it was necessary to postpone the Passover, fixed rules for the calendar were made. By this arrangement it became necessary to keep the second holydays, which had been celebrated in those places the messengers of the Nasi could not reach in time. Hillel ruled, however, that this practice had become hallowed by tradition, and that even henceforth the Jews living outside of Palestine should continue to celebrate two holydays.