We can scarcely, however, regard as a unit all the varying Mohammedan literatures of these many lands. The Persians, for example, retained their own language and wrote in it a literature of Mohammedan religious spirit, so important that we shall devote to it a later separate volume. Our present task, therefore, will confine itself to tracing through the Middle Ages the more strictly Arabian development. This includes first, the spread of literature and thought among the Arabs themselves, or among those people who completely adopted the Arabic faith and speech. Second, it includes the literature of the Moors, or semi-Arabic peoples, of North Africa and Spain. And third, it leads us to the Turks, the last Mohammedan conquerors, who took up and carried on Arabic tradition, though in a language and spirit more Tartar than Arabian. For the purely Arabic development, that is for the literature and thought that sprang directly from Mohammed's teaching, we turn first to the "Sunan," or traditions about Mohammed. After the prophet's death in A.D. 632, and while his followers were spreading his teachings by force of arms, they talked much of the doings and sayings of their adored master. Then, long after his own writings had been gathered in the official form of the Koran, a similar collection was made of what might be termed his unofficial teaching, that is of all his remembered words, the ideas which he had not proclaimed as inspired by God, but had given forth in ordinary conversation between man and man. The details of his life were also treasured. Thus sprang up the "Sunan," from which we may learn as much of Mohammed the man, and of the daily life and thought of his people, as from the Koran we learn of Mohammed the poet and of the poetic spirit of Arabia. For a long time the Arabs developed no other religious literature than this. Of the third leader of their new faith, the Caliph Omar, there is a well-known legend which may be untrue in fact but is intensely true to the fanatic spirit of the Caliph and his followers. It says that when Omar's armies conquered Egypt the scholars of Alexandria entreated him to protect the books of their great library, the largest in the world. Instead, Omar ordered the thousands of manuscripts to be used to feed the fires of the public baths; and he based the destruction upon this verdict: "If these books disagree with the Koran they are evil; if they agree they are unnecessary." The Arabic literary spirit was thus compelled to cling to its old pre-Mohammedan form. That is, it expressed itself only in brief personal poems, in skilfully phrased epigrams, satiric couplets, or "rubaiyat," called forth by a sudden occasion. A collection of the best known of these poems, gathered from successive ages of gay and dashing singers, is given at the close of our Arabic section.