Many years after Columbus's death, his son Fernando wrote that his father had studied geography (which was then called _cosmogony_) at the University of Pavia. Columbus himself never referred to Pavia nor to any other school; nor was it likely that poor parents could afford to send the eldest of five children to spend a year at a far-off university. Certain it is that he never went there after his seafaring life began, for from then on his doings are quite clearly known; so we must admit that while he may have had some teaching in childhood, what little knowledge he possessed of geography and science were self-taught in later years. The belief in a sphere-world was already very ancient, but people who accepted it were generally pronounced either mad or wicked. Long before, in the Greek and Roman days, certain teachers had believed it without being called mad or wicked. As far back as the fourth century B.C. a philosopher named Pythagoras had written that the world was round. Later Plato, and next Aristotle, two very learned Greeks, did the same; and still later, the Romans taught it. But Greece and Rome fell; and during the Dark Ages, when the Greek and Roman ideas were lost sight of, most people took it for granted that the world was flat. After many centuries the "sphere" idea was resurrected and talked about by a few landsmen, and believed in by many practical seamen; and it is quite possible that the young Cristoforo had learned of the theory of a sphere-world from Genoese navigators even before he went to sea. Wherever the idea originated is insignificant compared with the fact that, of all the men who held the same belief, Columbus alone had the superb courage to sail forth and prove it true. Columbus, writing bits of autobiography later, says that he took to the sea at fourteen. If true, he did not remain a seafarer constantly, for in 1472-73 he was again helping his father in the weaving or wool- combing business in Genoa. Until he started on his famous voyage, Columbus never kept a journal, and in his journal we find very little about those early days in Genoa. While mentioning in this journal a trip made when he was fourteen, Columbus neglects to state that he did not definitely give up his father's trade to become a sailor until 1475. Meanwhile he had worked as clerk in a Genoese bookshop. We know he must have turned this last opportunity to good account. Printing was still a very young art, but a few books had already found their way to Genoa, and the young clerk must have pored over them eagerly and tried to decipher the Latin in which they were printed. At any rate, it is certain that in 1474 or 1475 Cristoforo hired out as an ordinary sailor on a Mediterranean ship going to Chios, an island east of Greece. In 1476 we find him among the sailors on some galleys bound for England and attacked by pirates off the Portuguese Cape St. Vincent.