Mystici Corporis: Encyclical Letter Of Pope Pius XII On The Mystical Body Of Christ - Hardcoverby Pope Pius XII (Author) Mystici Corporis is an encyclical letter written by Pope Pius XII and published in 1943. The letter explores the concept of the Mystical Body of Christ, which refers to the unity of all Christians as members of one body under Christ. Pope Pius XII emphasizes that the Mystical Body is not just a metaphorical or symbolic idea, but a real and tangible reality that exists through the sacraments and the Church. He also discusses