The notion of “the frontier” is a profound one in European and American history. From the Rhine-Danube line of the late Roman Empire, to the eastern medieval German forests, to the Indies beyond the seas, to the New World and the Far West, the frontier has been, as Frederick Jackson Turner once suggested, as much spiritual as geographical in nature. We are a race that has, in a very real sense, been continually shocked out of our cyclic, stability tendencies by ever new horizons, each transcending and revolutionizing our cultural visions and expectations. The early voyages of Diaz, da Gama, Columbus, John Davis and Magellan, along with the later ones of Francis Drake, Abel Tasman and James Cook, were of a piece with Peary's and Amundsen's discoveries of the two Poles, with the search for the Northwest Passage, with Hillary's conquest of Everest and Neil Armstrong's walk on the Moon.