It was not merely the shutting up of China by the first Ming emperor, in 1368, that checked the intercourse between Europe and Asia. A still more baleful obstacle to all such intercourse had lately come upon the scene. In Asia Minor the beastly Turk, whose career had been for two centuries arrested by the Crusades, now reared his head again. The Seljukian had been only scotched, not killed; and now he sprang to life as the Ottoman, with sharper fangs than before. In 1365 the Turks established themselves in the Balkan peninsula, with Adrianople as their capital, and began tightening their coils about the doomed city of Constantine. Each point that they gained meant the strangling of just so much Oriental trade; for, as we have seen, the alliance of Constantinople with Genoa since 1261 had secured to the latter city, and to western Europe, the advantages of the overland routes from Asia, whether through the Volga country or across Armenia. When at length, in 1453, the Turks took Constantinople, the splendid commercial career of Genoa was cut with the shears of Atropos. At the same time, as their power was rapidly extending over Syria and down toward Egypt, threatening the overthrow of the liberal Mameluke dynasty there, the commercial prosperity of Venice also was seriously imperilled. Moreover, as Turkish corsairs began to swarm in the eastern waters of the Mediterranean, the voyage became more and more unsafe for Christian vessels. It was thus, while the volume of trade with Asia was, in the natural course of things, swelling year by year, that its accustomed routes were being ruthlessly cut off. It was fast becoming necessary to consider whether there might not be other practicable routes to "the Indies" than those which had from time immemorial been followed. Could there be such a thing as an "outside route" to that land of promise? A more startling question has seldom been propounded; for it involved a radical departure from the grooves in which the human mind had been running ever since the days of Solomon. Two generations of men lived and died while this question was taking shape, and all that time Cathay and India and the islands of Spices were objects of increasing desire, clothed by eager fancy with all manner of charms and riches. The more effectually the eastern Mediterranean was closed, the stronger grew the impulse to venture upon unknown paths in order to realize the vague but glorious hopes that began to cluster about these remote countries. Such an era of romantic enterprise as was thus ushered in, the world has never seen before or since. It was equally remarkable as an era of discipline in scientific thinking. In the maritime ventures of unparalleled boldness now to be described, the human mind was groping toward the era of enormous extensions of knowledge in space and time represented by the names of Newton and Darwin. It was learning the right way of putting its trust in the Unseen. CHAPTER IV.