Book excerpt: Sputnik. The first man on the moon. The Wright brothers and the Enola Gay. Television and e-mail. Dachau and Buchenwald. The Berlin Wall went up, and then it came crashing down. So did the stock market -- twice. It's been a century of elation and devastation -- of human greatness and of great tragedy. Here, from the archives of Time Life, is a poignant look at a century's worth of achievement, pathos, triumph, trends, and personalities. Here are the milestones and miracles, the inventions, explosions, heroes, and hurrahs that defined us in the 20th century. With hundreds of evocative images and countless moving stories, this chronicle recalls the faces, the moments, and the emotions of the century, as it draws to a close.