I do not understand.

I just finished reading my Christmas present from Agnieszka, "Inny świat" (or "Another World") by Gustaw Herling-Grudziński (written as Gustav Herling on the jacket....) It is his account of his life in the GULAG (a word which happens to be an acronym for Главное Управление Исправительно-Трудовых Лагерей и колоний, ГУЛАГ, Glavnoye Upravlyeniye ispravitel'no-trudovich LAGeryei i kolonii or Main Administration for Corrective Labor Camps and Colonies...... and actually refers to the prison system rather than the prisons themselves.....).

He ends the book with an amazing epilogue. He has been released from the prison as part of a much-belated general amnesty for Poles after the Sikorski-Mayski Agreement that allied Poland with the USSR against the Germans in 1941. He joined the Polish Army and, after the war, ended up in Rome. He was working at a government newspaper when he was approached by a former Polish Jewish cellmate, who had a similar story. The man had been the prisoner that announced the Fall of Paris to Gustaw in 1940. It signaled the end of all hope for the prisoners.... The then allied Germans and Russians had effectively conquered Europe; only London was left. The Poles would never be freed...... This man had been released under the same agreement as Gustaw, joined the Red Army, was injured, joined the Polish army and stormed Warsaw. There, he found all of his extended family dead, and he escaped to Italy.

Now, at the end, he has come to Gustaw for help. He wants to tell him a story of his life in the zone (what they call the GULAG), to which he would like Gustaw to simply reply "I understand". His story is that he was taken from a reasonable job in the zone and worked ragged in the Siberian forest for a few months. He was then taken before 4 of his fellow prisoners, Germans. The authorities wanted him to sign a statement claiming that he had heard the Germans discussing the impending fall of Moscow to Hitler. If he did as much, he would be allowed to leave the forest and go back to his previous, comparatively cushy, engineering job. He chose to sign the statement. He then heard the four Germans get shot.

Our hero Gustaw mulls the story over, remembering the depravity and horror to which he was driven, while in the zone. He decides that he has to make a similar choice to that of his friend. He can help his friend by condoning his actions and thus suffer -- this would mean reentering the realm of altered morals and lack of humanity that had existed during their incarceration -- or he can choose to escape this fate and remain a human being.

From the end of the book, after his friend has finished his story and is hoping for his "I understand":

'The choice was the same: it had been his life or the lives of the four Germans, now it was his peace or mine. No, I could not say it.
"Well?" he asked quietly.
I got up from the bed and without looking him in the eyes walked over to the window. With my back to the room I heard him going out and gently closing the door. I pushed the blind up. On the Piazza Colonna a cool breath of afternoon air had straightened the passers-by, as it would a field of corn bowed to the ground by drought. Drunk American and English soldiers walked along the pavements, pushing the Italians aside, picking up girls, looking for shade under the striped awnings of shops. Under the pillars of the corner house the black market was in full swing. The Roman "lazzaroni", small ragged war-children, dived in and out between the legs of enormous negroes in American uniforms. The war had ended a month ago. Rome was free, Brussels was free, Oslo was free, Paris was free. Paris, Paris, Paris....
I watched him as he walked out of the hotel, tripped across the road like a bird with a broken wing, and disappeared in the crowd without looking back.
The End'

Amazing book. Thank you Agnieszka.