First, we have to realize the peculiar relations between Europe, ancient and mediaeval, and the great empires of Eastern Asia. The two civilizations had never been in direct contact. Yet in a sense they were always connected. The Greeks and the Romans had at least vague reports of peoples who lived on the far eastern confines of the world, beyond even the conquests of Alexander the Great in Hindustan. It is certain, too, that Europe and Asia had always traded with one another in a strange and unconscious fashion. The spices and silks of the unknown East passed westward from trader to trader, from caravan to caravan, until they reached the Persian Gulf, the Red Sea, and, at last, the Mediterranean. The journey was so slow, so tedious, the goods passed from hand to hand so often, that when the Phoenician, Greek, or Roman merchants bought them their origin had been forgotten. For century after century this trade continued. When Rome fell, other peoples of the Mediterranean continued the Eastern trade. Genoa and Venice rose to greatness by this trade. As wealth and culture revived after the Gothic conquest which overthrew Rome, the beautiful silks and the rare spices of the East were more and more prized in a world of increasing luxury. The Crusades rediscovered Egypt, Syria, and the East for Europe. Gold and jewels, diamond-hilted swords of Damascus steel, carved ivory, and priceless gems,--all the treasures which the warriors of the Cross brought home, helped to impress on the mind of Europe the surpassing riches of the East. Gradually a new interest was added. As time went on doubts increased regarding the true shape of the earth. Early peoples had thought it a great flat expanse, with the blue sky propped over it like a dome or cover. This conception was giving way. The wise men who watched the sky at night, who saw the sweeping circles of the fixed stars and the wandering path of the strange luminous bodies called planets, began to suspect a mighty secret,--that the observing eye saw only half the heavens, and that the course of the stars and the earth itself rounded out was below the darkness of the horizon. From this theory that the earth was a great sphere floating in space followed the most enthralling conclusions. If the earth was really a globe, it might be possible to go round it and to reappear on the farther side of the horizon. Then the East might be reached, not only across the deserts of Persia and Tartary, but also by striking out into the boundless ocean that lay beyond the Pillars of Hercules. For such an attempt an almost superhuman courage was required. No man might say what awful seas, what engulfing gloom, might lie across the familiar waters which washed the shores of Europe. The most fearless who, at evening, upon the cliffs of Spain or Portugal, watched black night settle upon the far-spreading waters of the Atlantic, might well turn shuddering from any attempt to sail into those unknown wastes.