Jews, Arabs became acquainted as early as the eighth century, some time before the learning of the Greeks was brought within their reach, with Indian medicine, astronomy, and poetry. Greek science itself they owed to Jewish mediation. Not only among Jews, but also among Greeks, Syrians, and Arabs, Jewish versatility gave currency to the belief that "all wisdom is of the Jews," a view often repeated by Hellenists, by the "Righteous Brethren" among the Arabs, and later by the Christian monks of Europe. The academies of the Jews have always been pervaded by a scientific spirit. As they influenced others, so they permitted the science and culture of their neighbors to act upon their life and work. There is no doubt, for instance, that, despite the marked difference between the subjects treated by Arabs and Jews, the peculiar qualities of the old Arabic lyrics shaped neo-Hebraic poetry. Again, as the Hebrew acrostic psalms demonstrably served as models to the older Syrian Church poets, so, in turn, Syriac psalmody probably became the pattern synagogue poetry followed. Thus Hebrew poetry completed a circuit, which, to be sure, cannot accurately be followed up through its historical stages, but which critical investigations and the comparative study of literatures have established almost as a certainty. In the ninth century a bold, venturesome traveller, Eldad ha-Dani,[23] a sort of Jewish Ulysses, appeared among Jews, and at the same time Judaism produced Sa'adia, its first great religious philosopher and Bible translator. The Church Fathers had always looked up to the rabbis as authorities; henceforth Jews were accepted by all scholars as the teachers of Bible exegesis. Sa'adia was the first of the rabbis to translate the Hebrew Scriptures into Arabic. Justly his work is said to "recognize the current of thought dominant in his time, and to express the newly-awakened desire for the reconciliation of religious practice, as developed in the course of generations, with the source of religious inspiration." Besides, he was the first to elaborate a system of religious philosophy according to a rigid plan, and in a strictly scientific spirit.[24] Knowing Greek speculations, he controverts them as vigorously as the _Kalâm_ of Islam philosophy. His teachings form a system of practical ethics, luminous reflections, and sound maxims. Among his contemporaries was Isaac Israeli, a physician at Kairwan, whose works, in their Latin translation by the monk Constantine, attained great reputation, and were later plagiarized by medical writers. His treatise on fever was esteemed of high worth, a translation of it being studied as a text-book for centuries, and his dietetic writings remained authoritative for five hundred years. In general, the medical science of the Arabs is under great obligations to him. Reverence for Jewish medical ability was so exaggerated in those days that Galen was identified with the Jewish sage Gamaliel. The error was