Ever since "Know Thyself" was inscribed at Delphi, Western philosophers have struggled to understand the relations between morality and self-interest. This edited volume of essays pushes forward one of the oldest and most important debates in philosophy. Is morality a check on self-interest or is it in one's self interest to be moral? Can morality and self-interest be understood independently of each other? Christopher Morris, Mathias Risse, Richard Joyce, David Schmidtz, Thomas Nagel, Samuel Scheffler, Stephen Finlay, Terence Irwin Ralph Wedgwood, Julia Annas, W.D. Falk, Paul Bloomfield, Joel Kupperman, Michael Stocker,