Jan is understandably moved by his memories as he revisits his nightmares by train and car, and retains, throughout his sober recollection, a tough, fighting spirit.
His friend, Arnost Lustig, has his own way of dealing with the trauma of Auschwitz, which he survived, though his family did not. Arnost's way is to embrace life, to find the sunny side, to praise eros, to make up through imagination what the mean world took from him as a child. After Hitler's camps, Lustig became a member of the Communist Party just long enough to recognize that the new ideology was no better than the Hitlerism when it came to its enemies. At some point he explains his personality as a sun dial, 23 hours and 59 minutes of which is dedicated to life, with one minute of darkness. That minute is the thought of what his father must have felt and thought as he was being gassed at Auschwitz.
Jan, on the other hand, rejects Arnost's jocularity and spontaneity as an unnecessary and possibly harmful way to deal with the stark facts of the past. For him, the past is what it is: grave, tragic, unchangeable, unforgettable and never to be forgiven. Jan points out that the same people who welcomed Hitler into Czechoslovakia joined the Communist Party after the war. This great mass of conformists cared about nothing except their immediate well-being and were blind to the slaughter of their neighbors. All they wanted to do is survive.
Arnost, on the other hand, forgives them because they are human, weak and afraid. Throughout their journey, Arnost tries to banish the past with wine, jokes and laughter. He's also supremely annoying as he tries to interpret and embellish his friend's story for a novel he plans to write.
By the end of filming, the two friends are no longer speaking to each other. Jan cannot countenance Arnost's lightness, and Arnost cannot stand Jan's hardness. The two men are archetypal: Jan the fighter makes it impossible for injustice to prevail, but Arnost's clowning is also useful because he makes it possible for people to continue. Not forgetting is a guarantee of justice, forgiving is a guarantee for the future. The world needs both, and one is left in the end with profound questions about how life should be lived, and with the not entirely comfortable thought that one's character may precede one's experiences. Arnost gives up writing the novel, and Jan is doing Tai-Chi to control his anger.
No wonder documentaries are all the rage now. Real people are interesting in ways that "reality shows" and stupid sitcoms are not.