Among the landmarks which divide the Middle Ages from modern times the most conspicuous is the discovery of America by the Genoese captain Cristoforo Colombo in 1492. We shall discuss in the next chapter the nature and consequences of this discovery; the present deals briefly with the series of facts and events which led up to and prepared for it, and with the circumstances in which it was made. For Colombo's voyage, the most daring and brilliant feat of seamanship on record, though inferior to some others in the labour and difficulty involved in it, was but a link in a long chain of maritime enterprise stretching backward from our own times, through thirty centuries, to the infancy of Mediterranean civilisation. During this period the progress of discovery was far from uniform. Its principal achievements belong to its earliest stage, having been made by the Phoenicians, Greeks and Carthaginians before the Mediterranean peoples fell under the dominion of Rome. By that time, the coasts of Southern Europe and Asia, and of Northern Africa, together with at least one—perhaps more—among the neighbouring island groups in the Atlantic, were known in their general configuration, and some progress had been made in the task of fixing their places on the sphere, though their geographical outlines had not been accurately ascertained, and the longitude of the united terra firma of Europe and Asia was greatly over-estimated. In consequence of this excessive estimate Greek geographers speculated on the possibility of more easily reaching the Far East by a western voyage from the Pillars of Hercules; and this suggestion was occasionally revived in the earlier days of the Roman Empire. Yet from the foundation of that Empire down to the thirteenth century of our era, such a voyage was never seriously contemplated; nor was anything substantial added to the maritime knowledge inherited by the Middle Ages from antiquity. About the beginning of the twelfth century maritime activity recommenced, and by the end of the fifteenth a degree of progress had been reached which forced the idea of a westward voyage to the Far East into prominence, and ultimately brought it to the test of experience.