1. By Muslim scholars of the 10th century the sciences were divided into ‘Arab Sciences’ and ‘Old’- or ‘Non-Arab Sciences’. To the former belonged Grammar, Ethics and Dogmatics, History and Knowledge of Literature; to the latter Philosophy, Natural Science and Medicine. In the main the division is a proper one. The last-named branches are not only those which were determined the most by foreign influences, but those too which never became really popular. And yet the so called ‘Arab Sciences’ are not altogether pure native products. They too arose or were developed in places in the Muslim empire where Arabs and Non-Arabs met together, and where the need was awakened of reflecting on those subjects which concern mankind the most,—Speech and Poetry, Law and Religion,—in so far as differences or inadequacies appeared therein. In the mode in which this came about, it is easy to trace the influence of Non-Arabs, particularly of Persians; and the part taken by Greek Philosophy in the process asserts itself in ever-growing importance. 2. The Arabic language,—in which the Arabs themselves took particular delight, for its copious vocabulary, its wealth of forms and its inherent capability of cultivation,—was peculiarly fitted to take a leading position in the world. If it is compared, for example, with the unwieldy Latin, or even with the turgid Persian, it is found to be specially distinguished by the possession of short Abstract-forms,—a property of great service in scientific expression. It is capable of indicating the finest shades of meaning; but just because of its richly developed stock of synonyms, it offers temptations to deviate from the Aristotelian rule,—that the use of synonyms is not permissible in exact science. A language so elegant, expressive, and difficult withal, as Arabic was, necessarily invited much examination, when it had become the polite language of the Syrians and the Persians. Above all, the study of the Koran, and the recital and interpretation of it demanded profound attention to be devoted to the language. Unbelievers, also, may have thought that they could point out grammatical errors in the sacred Book; and therefore examples were gathered out of ancient poems and out of the living speech of the Bedouins, to support the expressions of the Koran. To these examples remarks were, no doubt, added upon grammatical accuracy in general. On the whole, the living usage formed the standard, but in order to save the authority of the Koran, it was certainly not applied without artifice. This proceeding was regarded, all the same, by simple believers, with a measure of suspicion. Masudi tells us even of some grammarians from Basra, who, when on a pleasure trip, took to going through a Koran Imperative, and for that reason(?) were soundly cudgelled by country folk engaged in date-gathering.