Yves R. Simon’s first book, Critique de la connaissance morale was originally published in 1934. An English version of this book has long been wanted, and here finally it is. Not only does this work put us at the dawn of Simon’s career, it is a fundamental contribution to moral philosophy. It starts at the beginning and goes on from there and if it does not attempt to reach the end we are struck by the clarity and order of the discussion. An understanding of this little book is essential for an orientation in Simon’s work in moral and political philosophy. A Critique of Moral Knowledge addresses a number of fundamentalset of problems: How does moral knowledge differ from other practical knowledge? What is the primary analogate of moral knowledge? What is the controlled range of meanings of moral knowledge? What is the relationship between the moral sense (Simon’s term for synderesis), moral philosophy, and the cognition embedded in action? Is politics part of moral philosophy or a neutral technique?