How a band of antislavery leaders recovered the radical philosophical inspirations of the first American Revolution to defeat the slaveholders' oligarchy in the Civil War. In their struggle against the slaveholding oligarchy of their time, America's antislavery leaders found their way back to the rationalist, secularist, and essentially atheist inspiration for the first American Revolution. Frederick Douglass's unusual interest in radical German philosophers and Abraham Lincoln's buried allusions to the same thinkers are but a few of the clues that underlie this propulsive philosophical detective story. With fresh takes on forgotten thinkers like Theodore Parker, the excommunicated Unitarian minister who is the original source of some of Lincoln's most famous lines, Matthew Stewart tells the story of the battle between America's philosophical radicals and the conservative counterrevolution that swept the American republic in the first decades of its existence and persists in new forms up to the present day. In exposing the role of Christian nationalism and the collusion between northern economic elites and slaveholding oligarchs, An Emancipation of the Mind demands a significant revision in our understanding of the origins and meaning of the struggle over slavery in America—and offers a fresh perspective on struggles between democracy and elite power today.