The letter Martin Luther King wrote from his Birmingham jail cell is considered a masterpiece of American moral argument. This hour, we’ll delve deeply into King’s thought process with Barnard College professor Jonathan Rieder, author of Gospel of Freedom: Martin Luther King, Jr.’s Letter from Birmingham Jail and the Struggle That Changed a Nation (Bloomsbury Press). Rieder will take part in the Dallas Institute’s 10th MLK Symposium Jan. 19 at City Performance Hall.