Of this presumptuous system, the strangest part was its logic, the nature of its proofs. It relied upon miracle-evidence. A fact was supposed to be demonstrated by an astounding illustration of something else! An Arabian writer, referring to this, says: "If a conjurer should say to me, 'Three are more than ten, and in proof of it I will change this stick into a serpent,' I might be surprised at his legerdemain, but I certainly should not admit his assertion." Yet, for more than a thousand years, such was the accepted logic, and all over Europe propositions equally absurd were accepted on equally ridiculous proof. Since the party that had become dominant in the empire could not furnish works capable of intellectual competition with those of the great pagan authors, and since it was impossible for it to accept a position of inferiority, there arose a political necessity for the discouragement, and even persecution, of profane learning. The persecution of the Platonists under Valentinian was due to that necessity. They were accused of magic, and many of them were put to death. The profession of philosophy had become dangerous--it was a state crime. In its stead there arose a passion for the marvelous, a spirit of superstition. Egypt exchanged the great men, who had made her Museum immortal, for bands of solitary monks and sequestered virgins, with which she was overrun. CHAPTER III. CONFLICT RESPECTING THE DOCTRINE OF THE UNITY OF GOD.--THE FIRST OR SOUTHERN REFORMATION. The Egyptians insist on the introduction of the worship of the Virgin Mary--They are resisted by Nestor, the Patriarch of Constantinople, but eventually, through their influence with the emperor, cause Nestor's exile and the dispersion of his followers. Prelude to the Southern Reformation--The Persian attack; its moral effects. The Arabian Reformation.--Mohammed is brought in contact with the Nestorians--He adopts and extends their principles, rejecting the worship of the Virgin, the doctrine of the Trinity, and every thing in opposition to the unity of God.-- He extinguishes idolatry in Arabia, by force, and prepares to make war on the Roman Empire.--His successors conquer Syria, Egypt, Asia Minor, North Africa, Spain, and invade France. As the result of this conflict, the doctrine of the unity of God was established in the greater part of the Roman Empire-- The cultivation of science was restored, and Christendom lost many of her most illustrious capitals, as Alexandria, Carthage, and, above all, Jerusalem.