Hell consists in man's being unwilling to receive anything, in his desire to be self-sufficient. It is the expression of enclosure in one's being alone. These depths accordingly consist by nature of just this: that man will not accept, will not take anything, but wants to stand entirely on his own feet, to be sufficient unto himself. If this becomes utterly radical, then man has become the untouchable, the solitary, the reject.
--Cardinal Joseph Ratzinger (Pope Benedict XVI), Introduction to Christianity, 1968