Thomas Hobbes's Leviathan is one of the most important philosophical texts in the English language, and one of the most influential works of political philosophy ever written. This Introduction accompanies the first critical edition based on a full study of the manuscript and printing history, and the first edition to place the English text side by side with Hobbes's later Latin version of it. The volume provides a path-breaking account of the work's context, sources, and textual history. Noel Malcolm's definitive work will set the study of Hobbes's masterwork on a new basis.