Intellectual Exploration as Geographical Exploration

My own field of physics is passing today through a phase of exuberant freedom, a phase of passionate prodigality. Sometimes as I listen to the conversation of my young colleagues at Princeton, I feel as if I am lost in a rain forest, with insects and birds and flowers growing all around me in intricate profusion, growing too abundantly for my sixty-year-old brain to comprehend. But the young people are at home in the rain forest and walk confidently along trails which to me are almost invisib...