The thirteenth century ended with the triumph of Islam and the extinction of the tiny Christian kingdoms of Palestine. Before the following century was halfway through, a Moslem army had set foot on European soil in the East, and that at the invitation of a Christian. A few years later, an Ottoman garrison at Gallipoli was evidence enough that the Byzantine Empire, long since shorn of its Asiatic provinces, was now threatened in its very capital. Anything like a systematic account of the contents of the Cribratio would need to be preceded by an outline of Nicolas’s philosophy, since this is operative throughout. In accordance with a tradition at least as early as John of Damascus, Mohammed is presented as a Christian heretic. An expelled monk, Sergius by name, went to Mecca, where he preached his Nestorian version of Christianity to Jews and idolaters.