_The Revival of Letters._ The first restorers of learning in Europe were the Arabians, who, in the course of their Asiatic conquests, became acquainted with some of the ancient Greek authors, discovered their merits, and had them translated into Arabic, esteeming those principally which treated of mathematics, physics, and metaphysics. They disseminated their knowledge in the course of their conquests, and founded schools and colleges in all the countries which they subdued. The western kingdoms of Europe became first acquainted with the learning of the ancients through the medium of those Arabian translations. Charlemagne caused them to be retranslated into Latin; and, after the example of the caliphs, founded universities at Bonona, Pavia, Osnaburg, and Paris. Similar efforts were made in England by Alfred; and to him we owe the establishment, or at least the elevation, of the university of Oxford. The first efforts, however, at literary improvement were marred by the subtleties of scholastic divinity. Perhaps the greatest and wisest literary character of the middle ages was an English friar, named Roger Bacon. This extraordinary individual was not only learned, but, what was more uncommon in those times, he was scientific. Hallam asserts that he was acquainted with the nature of gunpowder, though he deemed it prudent to conceal his knowledge. He saw the insufficiency of school philosophy, and was the first to insist on experiment and the observation of nature as the fittest instruments by which to acquire knowledge. He reformed the calendar, and made discoveries in astronomy, optics, chemistry, medicine, and mechanics.