Book excerpt: By anyone's reckoning, James Baker's years as Secretary of State contained some of the most pivotal events of the second half of the 20th century, and few men played as crucial a role in so many of them as did Baker. This candid, revealing account offers readers a unique perspective on such world-shaking events as the fall of the Eastern Bloc, the invasion of Panama, the Gulf War, and the birth of freedom in South Africa. Photos.