Babylonian literature went back to a remote date. The age of Sargon of Akkad was already a highly literary one, and the library he founded at Akkad contained works which continued to be re-edited down to the latest days of Babylonian literature. Every great city had its library, which was open to every reader, and where the books were carefully catalogued and arranged on shelves. Here too were kept the public records, as well as title-deeds, law-cases, and other documents belonging to private individuals. The office of librarian was held in honour, and was not unfrequently occupied by one of the sons of the king. Every branch of literature and science known at the time was represented. Theology was naturally prominent, as well as works on omens and charms. The standard work on astronomy and astrology, in seventy-two books, had been compiled for the library of Sargon of Akkad; so too had the standard work on terrestrial omens. There was also a standard work on medicine, in which medical prescriptions and spells were mixed together. Philological treatises were numerous. There were dictionaries and grammars for explaining the Sumerian language to Semitic pupils, interlinear translations of Sumerian texts, phrase-books, lists of synonyms, and commentaries on difficult or obsolete words and passages, besides syllabaries, in which the cuneiform characters were catalogued and explained. Mathematics were diligently studied, and tables of squares and cubes have come to us from the library of Larsa. Geography was represented by descriptions of the countries and cities known to the Babylonians, natural history by lists of animals and birds, insects and plants. The Assyrians were endowed with a keen sense of history, and had invented a system of reckoning time by means of certain officers called _limmi_, who gave their names to their years of office. The historical and chronological works of the Assyrian libraries are therefore particularly important. They have enabled us to restore the chronology of the royal period of Israelitish history, and to supplement the Old Testament narrative with the contemporaneous records of the Assyrian kings. The Babylonians were less historically exact, perhaps because they had less of the Semitic element in their blood; but they, too, carefully kept the annals of their kings, and took a deep interest in the former history of their country.