Thither the young Ṭabarí came to complete his education. He travelled by way of Rayy to Baghdád, visited other neighbouring towns, and extended his tour to Syria and Egypt. Although his father sent him a yearly allowance, it did not always arrive punctually, and he himself relates that on one occasion he procured bread by selling the sleeves of his shirt. Fortunately, at Baghdád he was introduced to ‘Ubaydulláh b. Yaḥyá, the Vizier of Mutawakkil, who engaged him as tutor for his son. How long he held this post is uncertain, but he was only twenty-three years of age when his patron went out of office. Fifteen years later we find him, penniless once more, in Cairo (876-877 A.D.). He soon, however, returned to Baghdád, where he passed the remainder of his life in teaching and writing. Modest, unselfish, and simple in his habits, he diffused his encyclopædic knowledge with an almost superhuman industry. During forty years, it is said, he wrote forty leaves every day. His great works are the _Ta’ríkhu ’l-Rusul wa-’l-Mulúk_, or 'Annals of the Apostles and the Kings,' and his _Tafsír_, or 'Commentary on the Koran.' Both, even in their present shape, are books of enormous extent, yet it seems likely that both were originally composed on a far larger scale and were abbreviated by the author for general use. His pupils, we are told, flatly refused to read the first editions with him, whereupon he exclaimed: "Enthusiasm for learning is dead!" The History of Ṭabarí, from the Creation to the year 302 A.H. = 915 A.D., is distinguished by "completeness of detail, accuracy, and the truly stupendous learning of its author that is revealed throughout, and that makes the Annals a vast storehouse of valuable information for the historian as well as for the student of Islam."[661] It is arranged chronologically, the events being tabulated under the year (of the Muḥammadan era) in which they occurred. Moreover, it has a very peculiar form. "Each important fact is related, if possible, by an eye-witness or contemporary, whose account came down through a series of narrators to the author. If he has obtained more than one account of a fact, with more or less important modifications, through several series of narrators, he communicates them all to the reader _in extenso_. Thus we are enabled to consider the facts from more than one point of view, and to acquire a vivid and clear notion of them."[662] According to modern ideas, Ṭabarí's compilation is not so much a history as a priceless collection of original documents placed side by side without any attempt to construct a critical and continuous narrative. At first sight one can hardly see the wood for the trees, but on closer study the essential features gradually emerge and stand out in bold relief from amidst the multitude of insignificant circumstances which lend freshness and life to the whole. Ṭabarí suffered the common fate of standard historians. His work was abridged and popularised, the _isnáds_ or