This comes as a huge surprise. Major news sources have passed on the Vatican’s announcement. The Vatican announcement is here. I am not going to speculate about “deeper motives” for his resignation. We should take him at his words since he is an honest man.
I watched my father decline in his later years. His mind was still sharp but his physical well-being was not cooperating. I think this is an act of great humility. He is a precise and exacting German who does not want to do anything if it is not done well. He knows his limitations and is stepping down in great humility and in his love for the Church. This is my take.
Canon Law 332, no. 2 states that a Pope can resign but no one can receive his resignation. “If it should happen that the Roman Pontiff resigns his office, it is required for validity that he makes the resignation freely and that it be duly manifested, but not that it be accepted by anyone.”
In his speech, Pope Benedict says: “After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry.”
Excellent discussion between Mark Brumley (President of Ignatius Press) and Fr. Joseph Fessio SJ (student and friend of Card. Ratzinger)