No phrase in American letters has had a more profound influence on church-state law, policy, and discourse than Thomas Jeffersons wall of separation between church and state, and few metaphors have provoked more passionate debate. Introduced in an 1802 letter to the Danbury, Connecticut Baptist Association, Jeffersons wall is accepted by many Americans as a concise description of the U.S. Constitutions church-state arrangement and conceived as a virtual rule of constitutional law. Despite the enormous influence of the wall metaphor, almost no scholarship has investigated the text of the Danbury letter, the context in which it was written, or Jeffersons understanding of his famous phrase. offers an in-depth examination of the origins, controversial uses, and competing interpretations of this powerful metaphor in law and public policy.