In his book "Principles of Catholic Theology", Pope Benedict XVI (then Cardinal Ratzinger) assessed the range of "possibilities that are open to Christian ecumenism." He characterized the "maximum demand" of the West as the recognition by the East of and submission to the "primacy of the bishop of Rome in the full scope of the definition of 1870..." The "maximum demand" of the East was described as a declaration by the West of the 1870 doctrine of papal primacy as erroneous along with the "removal of the Filioque from the Creed and including the Marian dogmas of the nineteenth and twentieth centuries." Ratzinger asserted that "(n)one of the maximum solutions offers any real hope of unity." Ratzinger wrote that "Rome must not require more from the East than had been formulated and what was lived in the first millennium." He concluded that "Reunion could take place in this context if, on the one hand, the East would cease to oppose as heretical the developments that took place in the West in the second millennium and would accept the Catholic Church as legitimate and orthodox in the form she had acquired in the course of that development, while on the other hand, the West would recognize the Church of the East as orthodox in the form she has always had."