John Wilkins writes in the TimesOnline,

“All human beings, the philosopher Donald MacKinnon used to tell his Cambridge students, have a desire for a true judgment on the lives they have lived. They want to submit to the verdict of an arbitrator who will have inner knowledge of the cards they were dealt, and the conclusions they drew about the way to play them; who will comprehend at the deepest level their motives and intentions in face of the pressures upon them and who will have mercy when they whisper the truth.
Such a judge is not obtainable on this earth, MacKinnon observed. This would seem to be what Pope Benedict XVI is driving at in his recent encyclical letter on hope, Spe Salvi, when he says that “I am convinced that the question of justice constitutes the essential argument, or in any case the strongest argument, in favour of faith in eternal life”. This last section of the encyclical, in which the Pope also reflects on human suffering, has resonance in Lent.
The encyclical, like its predecessor Deus Caritas Est, on love, is written in a beautifully precise, taut style. Here is a German professor at his best, drawing from his reflection on a wide spectrum of ideas as he contends with the atheist current in the West which, he is convinced, will be ruinous. The hope on which he dwells is specifically Christian hope. “

Wow. Here is the English translation of the encyclical, if of interest.
The whole commentary, entitled “Divine justice is perfect and tempered with mercy,” is certainly worth a read.