Early in the Leviathan, in chapter 2 “Of imagination,” Hobbes introduces the idea of an enemy as a kind of angry dreaming: “when we sleep, the over heating of the same parts causeth Anger, and raiseth up in the brain the Imagination of an Enemy.” For Hobbes, dreaming is (as he tells us in chapter 3) characteristic of unguided thought and unguided thought just is “commonly the thoughts of men!”