ARABIAN SCIENCE.--A great literary and philosophical fact in the eighth century was the invasion of the Arabs. Mahometans successively invaded Syria, Persia, Africa, and Spain, forming a crescent, the two points of which touched the two extremities of Europe. Inquisitive and sagacious pupils of the Greeks in Africa and Asia, they founded everywhere brilliant universities which rapidly acquired renown (Bagdad, Bassorah, Cordova, Granada, Seville, Murcia) and brought to Europe a new quota of science; for instance, all the works of Aristotle, of which Western Europe possessed practically nothing. Students greedy for knowledge came to learn from them in Spain; for instance, Gerbert, who developed into a man of great learning, who taught at Rheims and became Pope. Individually the Arabs were often great philosophers, and at least the names must be mentioned of Avicenna (a Neoplatonist of the tenth century) and Averroes (an Aristotelian of the twelfth century who betrayed tendencies towards admitting the eternity of nature, and its evolution through its own initiative during the course of time). Their doctrines were propagated, and the ancient books which they made known became widely diffused. From them dates the sway of Aristotle throughout the middle ages. ST. ANSELM.--St. Anselm, in the eleventh century, a Savoyard, who was long Abbot of Bec in Normandy and died Archbishop of Canterbury, is one of the most illustrious doctors of philosophy in the service of theology that ever lived. "A new St. Augustine" (as he has been called), he starts from faith to arrive at faith after it has been rendered sensible to reason. Like St. Augustine he says: "I believe in order to understand" (well persuaded that if I never believed I should never understand), and he adds what had been in the thought of St. Augustine: "I understand in order to believe." St. Anselm proved the existence of God by the most abstract arguments. For example, "It is necessary to have a cause, one or multiple; one is God; multiple, it can be derived from one single cause, and that one cause is God; it can be a particular cause in each thing caused; but then it is necessary to suppose a personal force which must itself have a cause and thus we work back to a common cause, that is to say to a single one." He proved God again by the proof which has remained famous under the name of the argument of St. Anselm: To conceive God is to prove that He is; the conception of God is proof of His existence; for every idea has its object; above all, an idea which has infinity for object takes for granted the existence of infinity; for all being finite here below, what would give the idea of infinity to the human mind? Therefore, if the human brain has the idea of infinity it is because of the existence of infinity. The argument is perhaps open to difference of opinion, but as proof of a singular vigour of mind on the part of its author, it is indisputable.