Hank Kruse talks about the theology of the liturgy in the work of Karl Ratzinger (Pope Benedict XVI). We mention Origen of Alexandria, Tripp Parker, John Calvin, Hans Van Balthasar, Augustine, Thomas Aquinas, Berengarius, Bonaventure, Justin Martyr, Ignatius of Antioch, and more. Karl Ratzinger - Introduction to Christianity: https://www.amazon.com/Introduction-Christianity-2nd-Communio-Books/dp/1586170295