Contact with the Orient has always been an important factor in the history of Europe. Centers of civilization and of political power have shifted with every decisive change in the relations of East and West. Opposition between Greek and barbarian may be regarded as the _motif_ of Greek history, as it is a persistent refrain in Greek literature. The plunder of Asia made Rome an empire whose capital was on the Bosphorus more centuries than it was on the Tiber. Mediaeval civilization rose to its height when the Italian cities wrested from Constantinople the mastery of the Levantine trade; and in the sixteenth century, when the main traveled roads to the Far East shifted to the ocean, direction of European affairs passed from Church and Empire to the rising national states on the Atlantic. The history of America is inseparable from these wider relations. The discovery of the New World was the direct result of European interest in the Far East, an incident in the charting of new highways for the world's commerce. In the thirteenth and fourteenth centuries Europeans first gained reliable knowledge of Far Eastern countries, of the routes by which they might be reached, above all of the hoarded-treasure which lay there awaiting the first comer. Columbus, endeavoring to establish direct connections with these countries for trade and exploitation, found America blocking the way. The discovery of the New World was but the sequel to the discovery of the Old. From the ninth to the eleventh century the people of Western Europe had lived in comparative isolation. With half the heritage of the Roman Empire in infidel hands, the followers of the Cross and of the Crescent faced each other, like hostile armies, across the sea. The temporary expansion of the Frankish Empire ceased with the life of Charlemagne, and under his successors formidable enemies closed it in on every hand. Barbarian Slav and Saxon pressed upon the eastern frontier, while the hated Moslem, from the vantage of Spain and Africa, infested the Mediterranean and threatened the Holy City. Even the Greek Empire, natural ally of Christendom, deserted it, going the way of heresy and schism.