This mystical doctrine flourished chiefly in Palestine, where the real study of the Talmud was languishing; little by little it made its way into Babylonia. This became apparent on the occasion of the election of a principal of the Pumbeditha academy (814). The best claim to this office was that advanced by a certain Mar-Aaron (ben Samuel), by reason of his erudition and on account of his having acted up till then as chief judge. Nevertheless, preference was given to the claim of a rival, the aged Joseph bar Abba, who was far inferior to him in learning; the reason of this preference being that the latter was an adept in mysticism, and was believed to be favored with the intimacy of the prophet Elijah. One day when this same Joseph bar Abba was presiding at a public meeting, he exclaimed with rapture, "Make room for the old man who is just coming in." The eyes of all present were immediately turned to the entrance, and those to the right of the principal respectfully stepped aside. They saw no one enter, however, and were therefore all the more positively convinced that the prophet Elijah had entered invisible, had seated himself on the right of his friend Joseph, and had been present during the whole of his discourse. After that time no one dared occupy the place at the side of the principal of the Pumbeditha academy, for it had been honored and hallowed by Elijah, and it became the custom to leave it vacant. Joseph's successor, Mar-Abraham ben Sherira (816-828), was likewise a mystic. It was said that he could foresee the future from the rustling of palm leaves on a calm day.