Originally published anonymously, ''Nature'' was the first modern essay to recommend the appreciation of the outdoors as an all-encompassing positive force. Emerson's writings were recognized as uniquely American in style and content, and launched the idea of going for a walk as a new way of looking at the world. Throughout history, some books have changed the world. They have transformed the way we see ourselves - and each other. They have inspired debate, dissent, war and revolution. They have enlightened, outraged, provoked and comforted. They have enriched lives - and destroyed them. Now Penguin brings you the works of the great thinkers, pioneers, radicals and visionaries whose ideas shook civilization and helped make us who we are.