"All first-rate criticism first defines what we are confronting," the late, great jazz critic Whitney Balliett once wrote. By that measure, the essays of Christopher Hitchens are in the first tier. For nearly four decades, Hitchens has been telling us, in pitch-perfect prose, what we confront when we grapple with first principles-the principles of reason and tolerance and skepticism that define and inform the foundations of our civilization-principles that, to endure, must be defended anew by every generation.