Book excerpt: From its origins in 1930s Marxism to its unprecedented influence on George W. Bush's administration, neoconservatism has become one of the most powerful, reviled, and misunderstood intellectual movements in American history. But who are the neocons, and how did this obscure group of government officials, pundits, and think-tank denizens rise to revolutionize American foreign policy?Political journalist Jacob Heilbrunn uses his intimate knowledge of the movement and its members to write the definitive history of the neoconservatives. He sets their ideas in the larger context of the decades-long battle between liberals and conservatives, first over communism, and now over the war on terrorism. And he explains why, in spite of their misguided policy on Iraq, they will remain a permanent force in American politics.