This gradual advance of the bishop of Rome in political influence associated him with the mighty memories of the “Eternal City,” and suggested the idea of a spiritual empire over all Christendom, which gradually became realized and quite changed the character of Christianity for near 800 years. Hurtful as it ultimately became, by reviving a universal despotism over conscience and freedom of thought, it was long powerful for good by giving a common centre to Europe, broken into fragments as it was by the rise of feudalism. That was disorganizing; this was centralizing, and kept the channels of communication open and the missionary spirit and the elements of a restored learning in activity. Its influence in commencing and carrying forward the crusades, which substantially broke the strength of feudalism, was of immense importance. 622—Mahomet arose in the Arabian peninsula, and his new religion spread with astonishing rapidity. In one hundred 732—years from the death of Mahomet the Saracens had established a vast empire, covering two thirds of the Roman empire, viz.: all of the old Persian empire, Egypt, and all of northern Africa and Spain, and threatened to inundate Europe. They poured a vast army over the Pyrenees into France. This was defeated in a great battle at Tours, by Charles Martel, who founded a new dynasty, replacing the Merovingian, called the Carlovingian, and made France the most powerful, as it became the leading, nation in Europe, for promoting civilization during many centuries.