This thesis is an attempt to show that the aristocratic regime, and aristocratic morality, is the origin of the idea of nature; that, at the point at which a historical aristocracy starts to decline, its defenders, in abstracting and radicalizing the case for aristocracy in the face of its critics, come upon the teaching of nature and the standard of nature in politics. It is precisely this teaching of nature, so corrosive of all convention and all morality, that is politically explosive, and that explains the deep connection between philosophy--the criminal study of nature outside the city and outside the myths and pieties of the regime--and tyranny--the criminal and feral regime of rule outside and above all law and all convention.