Pytheas, around whom centers the question of Thule, was considered for two thousand years the champion liar of antiquity. After perhaps the most overdue of rehabilitations, he is now in our books and belief an outstanding leader in Greek science and a foremost explorerthe earliest of the known great explorers. If he appears to us less than Columbus in some ways he appears greater in others, particularly as a scientist. He has been referred to as a Columbus with a flavor of Darwin; he appears to have been more nearly a composite of James Cook and Galileo.