"America goes not abroad, in search of monsters to destroy"--John Quincy Adams's famous words are often quoted to justify noninterference in other nations' affairs. Yet when he spoke them, Adams was not advocating neutrality or passivity but rather outlining a national policy that balanced democratic idealism with a pragmatic understanding of the young republic's capabilities and limitations. America's rise from a confederation of revolutionary colonies to a world power is often treated as inevitable, but Charles N. Edel's provocative biography of Adams argues that he served as the central...