Thomas Hobbes, the seventeenth-century English philosopher, is the subject of lively discussion among philosophers, historians, and political theorists today. Both as a participant in a revolutionary commonwealth and as a student of the science of human nature, Hobbes has achieved a new relevance to contemporary society. As the editors of this volume point out, moralists are apt to place him in the twentieth century, and historians are apt to portray him as an antique. The aim of these essays is to get an accurate account of how radical Hobbes was in his own revolutionary century.