The period since World War I is best described by the phrase,"the best of times, the worst of times." It witnessed remarkable achievements in science and technology, but was also marred by inhumanity and violence. It was a period in which Europe's dominance was undermined, the capitalist economy of the Western World was challenged by the emergence of Communism, the threat of the atom bomb loomed, and the world's population expanded at an alarming rate. Perhaps the most dramatic achievement of this period was the conquest of space and its triumphs. The half- century following WWI created a mood of anxiety that eroded the traditional values of loyalty and confidence in man's capacity to survive. Although the leaders of the period operated within lonely, hostile environments, they refused to be defeated. More significant than the opening of new continents, was the resurgence of man's spirit, the revival of confidence.