'Aeneas Silvius', Picolominia, the Sienese pope, Pius II; 1458-64) published 'The Description of Asia' in which he insisted that all seas were navigable and all lands habitable.  The pontiff believed that one could travel from Europe to Asia viaa the West.

There were many curious stories abroad in the years leading up to Columbus' voyage about sailing west to find more Atlantic islands, 'Antilla' and 'Brasil', for example, or St Ursula's island or St Brendan's. The sea then seemed a magical place, full of extraordinary possibilities, while interest in the idea of the 'Antipodes' had been excited by the publication in 1469 in Spanish of the geography of the Greek Strabo; that first-century geographer had even talked of the possibility of 'sailing direct from Spain to the Indies'.²⁸ About a dozen Portuguese voyages were despatched westwards between 1430 and 1490. Perhaps some sailors of that nation would have heard of the medieval Norse expeditions to Greenland, Vinland and North America. After all, the last Greenlander of Norse origin only died in the fifteenth century.

That the earth was round had been realised for many generations. The Greek astronomers of Miletus had even thought, about 500 bc, that the world was a sphere. That view had been advanced by the geometrician Pythagoras. Though much of Greek learning was later lost, the Catholic Church had accepted this hypothesis by about 750 ad and, in the fifteenth century, the 'sphericity' of the planet was generally agreed. Only a few ignorant people still tried to maintain that it was flat.