Wüstenfeld and the bibliographers that followed him have evidently derived their information concerning these MSS. from the catalogues of the Bodleian Library and of the Bibliothèque Nationale. No mediaeval bibliographer has up to the present been found who mentions this book of Maimonides.[367] Wüstenfeld’s usual authority for his statements is the great thirteenth-century medical biographer, Ibn Abi ‘Uṣaibia. But, though the latter gives a life of the Hebrew physician and a list of his writings,[368] he makes no mention of the _Tractatus de Causis et Indiciis Morborum_. Moreover, this _Tractatus_ has no place in Haji Khalfa’s admirable bibliography of Arabic works, which contains notices of four books bearing the title _De Causis et Indiciis Morborum_, not one of which is by Maimonides. Lastly, neither the historian Al Qifty in his _Classes philosophorum et astronomorum et medicorum_,[369] nor Bar Hebraeus, who is said to have plagiarized him,[370] notice the work in their sketches of the physician’s life. The Bodleian MS. alleged to contain the _Tractatus_ is one of a collection of over seven hundred volumes bequeathed to the library on his death, November 2, 1713, by Narcissus Marsh, Archbishop successively of Cashel, Dublin, and Armagh. Most of his Oriental MSS. had been procured for him either in the East by Robert Huntington, Bishop of Raphoe and chaplain to the English merchants at Aleppo, or at the sale of Golius’s library at Leyden in October 1696.[371] Golius was a Dutch orientalist, born at Leyden in 1596. He studied medicine and Oriental languages at the University of Leyden, and after leaving it he accompanied a French embassy to Morocco in 1622. He remained in Morocco for two years, and while there collected various MSS. On his return in 1624 he was appointed to the Chair of Arabic at Leyden, but was allowed a period of leave for travel in the East before taking up his appointment. He took with him a grant of money for the purchase of MSS., and these to the number of over two hundred are now deposited in the University Library at Leyden. On several occasions during his travels in Arabia attempts were made by Arab chiefs to detain him for his medical knowledge, but he returned safely and later wrote a number of works mainly concerned with Arabic. He died in 1667. Among the MSS. which Golius himself procured for the Leyden Library was that of the _Delectus_. It is at least unlikely therefore that such a profound Arabist, who was also a medical man, would have bought the Bodley fragment for a genuine work of Maimonides; the primary responsibility for the error thus probably rests with Huntington. However that may be, it was Uri, in his catalogue of the Bodleian MSS., who first published the error, and from him it was passed on to the modern bibliographers.