With the revival of classical learning in the Renaissance, geographical theories also became less wildly imaginative than in the medieval period, the charts of which, though beautifully colored and highly decorated with fauna and flora, show no such accurate knowledge even of the old world as do those of the great geographer Ptolemy, who lived a thousand years before. Ptolemy (200 A.D.), in company with the majority of learned men since Aristotle, had declared the earth to be round and had even estimated its circumference with substantial accuracy, though he had misled later students by picturing the Indian Ocean as completely surrounded by Africa, which he conceived to extend indefinitely southward and join Asia on the southeast, leaving no sea-route open from the Atlantic. There was another body of opinion of long standing, however, which outlined Africa much as it actually is. Friar Roger Bacon, whose interest in the compass has already been mentioned, collected statements of classical authorities and other evidence to show that Asia could be reached by sailing directly westward, and that the distance was not great; and this material was published in Paris in a popular _Imago Mundi_ of 1410. In general, the best geographical knowledge of the period, though it underestimated the distance from Europe westward to Asia and was completely ignorant of the vast continents lying between, gave support to the theories which the voyages of Diaz, Vasco da Gama, and Columbus magnificently proved true. When the best sailors of the time were Italians, and when astronomical and other scientific knowledge of use in navigation was largely monopolized by Arabs and Jews, it seems strange that the isolated and hitherto insignificant country of Portugal should have taken, and for a century or more maintained primacy in the great epoch of geographical discovery. The fact is explained, not so much by her proximity to the African coast and the outlying islands in the Atlantic, as by the energetic and well-directed patronage which Prince Henry the Navigator (1394-1460) extended to voyages of exploration and to the development of every branch of nautical art. The third son of John the Great of Portugal, and a nephew on his mother's side of Henry IV of England, the prince in 1415 led an armada to the capture of Ceuta from the Moors, and thereafter, as governor of the conquered territory and of the southern province of Portugal, settled at Saigres near Cape St. Vincent. On this promontory, almost at the western verge of the known world, Henry founded a city, Villa do Iffante, erected an observatory on the cliff, and gathered round him the best sailors, geographers and astronomers of his age. [Illustration: PORTUGUESE VOYAGES AND POSSESSIONS]