When he resigned, Benedict cited his advanced age as the reason, saying he no longer had the strength for "an adequate exercise of the Petrine ministry".
BBC: Ex-Pope Benedict returns to Vatican
2.
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.
CNN: Full text of Pope Benedict XVI's declaration
3.
"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, " he added.