With Hitler's Nuremberg Laws depriving Jews of German citizenship, and mounting restrictions against Jewish economic activity, Pope Pius XI in June 1938 asked an American Jesuit, Father John LaFarge, to secretly begin work drafting an encyclical condemning racism and anti-semitism. By September 1938, the draft encyclical Humani Generis Unitas (The Unity of the Human Race) was ready. But after the death of Pius XI in February 1939, the draft encyclical was shelved, and until recently the Vatican was still denying that it existed. Was the "Secret Encyclical" a lost opportunity for the Church to condemn antisemitism? Why wasn't it published by Pope Pius XII? And could its publication have prevented the Holocaust?