The great explorations before the Fifteenth Century have largely been lost. Some attempts to reconstruct possible voyages from Egypt, Ireland, Scandinavia and South America give us some idea of how ancient navigation may have been conducted and how man went forth into the unknown and terrible seas. Surviving fragments of maps from some of these early voyages have remained to tantalize us, but it was the Portuguese explorers who began to record voyages of exploration by writing detailed pilots for their own use in repeating voyages and avoiding dangers. These pilots were very valuable documents guarded with care. Of all the Portuguese navigators who sailed to Japan and the Americas, Africa and India, Vasco da Gama is perhaps the most widely known.