[Sidenote: Secret of papal strength] Never has the world seen such an enduring system as the papacy. Patterned so nearly after the truth of God, and resembling so closely, both in church government and educational principles, the plan delivered to the chosen nation, that only an expert, guided by the Spirit of truth, could judge between the true and the counterfeit, it had, as had the Jews before them, replaced the life by the mere form. Nevertheless, so firmly laid was the foundation, and so substantially built were the walls, that for centuries it baffled all attempts at overthrow. This structure had as its foundation an _educational system_; the mortar which held the bricks in the wall was _educational methods_, and should the building fall, the foundation itself must be attacked. As a civil power, the papacy was periodically attacked by ambitious kings and princes; but these shocks scarcely disturbed the serenity of the papal head, so firm was his throne. The sword of the Mohammedans was broken at Tours; and the Crescent, instead of advancing to the full by encircling the Mediterranean, waned as its light receded to the shores of Africa and the west of Asia. [Sidenote: The revival of learning] What the Turk could not do by force of arms, he did in another way. In 1453 Constantinople fell into the hands of the calif, yet this did not affect the strength of the papal hierarchy. But as the Turk came into Greece, Greek art and literature fled to Italy. Here is the attack on the papacy which came from the east. Painter says: “The revival of classical learning, which had its central point in the downfall of Constantinople in 1453, exerted a favorable influence. It opened the literary treasures of Greece and Rome, provided a new culture for the mind, awakened dissatisfaction with the scholastic teaching of the church, and tended to emancipate thought from subjection to ecclesiastical authority.”[110] The taking of Constantinople did still more toward hastening the Reformation. Venice had controlled the commerce of the eastern Mediterranean, but Turkish supremacy in those waters transferred that power to her rival, Genoa, on the other side of Italy; and from this latter center began the search for a western passage to the East Indies which led to the accidental discovery of America. [Sidenote: Greek classics]