When the Seljuk Turks, with their fierce animosity towards Christendom, had settled like a curtain between East and West, the dangers and expense of trading and commerce with Arabia and Asia Minor of course increased. Venice and Genoa still brought back shiploads of silks, spices, and perfumes for Western markets, but the price of these goods was increased by the tolls paid to Turkish sultans and emirs for leave to transfer merchandise from camels to trading-sloops. Then came the fall of Constantinople, when Venice, by a treaty with ‘the Conqueror’ in the following year, appeared to secure wonderful trading privileges. Mohammed, however, made such promises only to break them when convenient, and, so soon as he could afford to do so, because he was securely established in Europe, the tolls he demanded became heavier, not lighter, the restrictions he placed upon trade more and more galling to Christian merchants, until the usual purchasers of Venetian goods grew exasperated at prices that doubled and trebled continually. [Sidenote: Voyage and Discovery] There were but two methods of avoiding this ever-increasing policy of exploitation apart from doing without such luxuries: either a complete conquest of the Turks, that would compel them to open up afresh the old caravan routes to the East; or else the discovery of a new route that would avoid their dominions altogether. Largely through the blind selfishness of Mediterranean cities, and especially of Venice, we have seen that the golden opportunity of aiding the Byzantine Empire had been lost for ever. Thus the first method failed. It remains to deal with the second, the voyages of discovery with which the Middle Ages fittingly close. [Sidenote: Henry ‘the Navigator’] Towards the end of the fourteenth century there was born in Portugal a prince, Henry, third son of King John I, and grandson by an English mother of John of Gaunt, Duke of Lancaster. While he was still a boy this prince earned fame for his share in the capture of Ceuta, a Moorish town exactly opposite Gibraltar on the North African coast. To the ordinary Portuguese mind this conquest raised hopes of a gradual absorption of the southern Mediterranean seaboard, possibly of competition in the Levant with Genoa and Venice; but Prince Henry saw farther than ordinary minds. The problem that he set himself and any one, Arab or European, who seemed likely to supply a solution was--What would happen if, instead of entering the Mediterranean, Portuguese ships were to sail due south? How big was this unknown stretch of land called Africa, in the maps of which geographers hid their ignorance by placing labels, such as ‘Here are hippografs! Here are two-headed monsters!’? Would it not be possible to reach the far-famed wonders of Cathay by sailing first south and then east round Africa, thus avoiding trade routes through Syria and southern Russia?