Russia—their small numbers were soon absorbed into the older populations. Thus the whole defensive strength of Europe could be thrown against the south-eastern danger. But as the European civilisation gained momentum, there was energy to spare upon the ocean frontage; Venice and Austria sufficed for the later struggle against the Turks.
After the essays, without practical result, of the Norsemen to force their way through the northern ice of Greenland, the Portuguese undertook to find a sea-way to the Indies round the coast of Africa. They were inspired to the venture by the lead of Prince Henry 'the Navigator,' half Englishman and half Portuguese. At first sight it seems strange that pilots like Columbus, who had spent their lives on coasting voyages, often going from Venice to Britain, should so long have delayed an exploration southward as they issued from the Straits of Gibraltar. Still more strange does it appear that when at last they had set themselves to discover the outline of Africa, it took them two generations of almost annual voyaging before Da Gama led the way into the Indian Ocean. The cause of their difficulties was physical. For a thousand miles, from the latitude of the Canary Islands to that of Cape Verde, the
