RABBI JONAH, of Cordova, the most eminent Jewish grammarian and lexicographer of the Middle Ages, known also among Hebrew authors as R. Merinos (Marinus), but now usually called by his Arabic name Abu '1 Walid Merwán ibn Janáh, was born at Cordova towards the close of the 10th century, but spent his youth partly at the neighbouring Jewish town of Lucena (Alisana), where he studied under Isaac ben Gikatila and Isaac ben Saul. He appears not to have returned to Cordova till after the death of the famous Hayyúj, the founder of a scientific Hebrew grammar based on the doctrine of triliteral roots. Though not a personal disciple of Hayyúj, Abu '1 Walid adopted the general principles of his system, and early applied himself to the task of completing and correcting the observations of his predecessor on the subject of weak roots. While engaged in these studies he retired from Cordova during the siege of the town by the Berber prince Suleiman (1013 ), and took up his residence in Saragossa, where he published his first work, the Kitáb el Mustalhik, so named because it contained an attempt to supply the omissions of Hayyúj. The Jews of Saragossa were not favourably disposed to the new philology, and the writings of Abu '1 Walid were not only displeasing to men of the old school, but involved him in bitter controversy with the professed disciples of Hayyüj, on whose views he had presumed to improve. The most formidable of these antagonists was Samuel Ibn Nagdela Hallevy, the prime minister of Granada. Abu '1 Walid had much to suffer from the rancour of so influential an opponent, but he persisted in his studies, which were finally crowned by the publication of the Kitab el Tankih, or " Book of Minute Research," a grammatical and lexicographical work of the first order, which is still consulted by scholars, and can never be opened without admiration for the range and precision of the author's scholarship and the soundness of his philological method. There is more Hebrew to be learned from Abu '1 Walfd than from all the later rabbins put together. Abu '1 Walid was essentially a philologist. He had essayed poetry in his youth, was read in philosophy, and not only practised as a physician but wrote on medicine; but the devotion of his life was concentrated on the exact verbal study of Scripture. Armed with a thorough knowledge of the language and grammatical system of the Arabs, as well as of the dialects of Jewish Aramaic, he studied the Biblical idiom in the light of the cognate Semitic tongues, and in a spirit of pure scholarship, free from traditional prejudice.

The extant minor works of R. Jonah have been published in Arabic with a French translation by J. andH. Derenbourg, Opuscules et Traitis d'Abou 'I- Walid, Paris, 1880. The first or grammatical part of the Kitdb el- Tankih has been published in the imperfect Hebrew version entitled Sefer Harikma by Goldberg, Frankfort-on-the-Main, 1856. The lexicographical part of the Kitab el-Usill, or Book of Roots, was published in Arabic by Neubauer, Oxford, 1875. For further details as to the life and works of Abu '1-Walid see Munk's articles in Journal Asiatique, 1850, 1851; and Derenbourg, op. cit.