This is the first new scholarly edition since the nineteenth century of one of the greatest works in the history of philosophy: David Hume's Enquiry concerning the Principles of Morals. It is the fourth volume of the Clarendon Hume Edition, which will be the definitive edition for the foreseeable future. In this elegant and lucid Enquiry Hume gives an accessible presentation of his fully developed ethical theory, that is to say his theory of the foundation of morality in human nature. He considered this work to be `of all my writings, historical, philosophical, or literary, incomparably the best'. The distinguished Hume scholar Tom Beauchamp presents an authoritative text accompanied by introduction, annotation, glossary, biographical sketches, bibliographies, and indexes.