Born on August 12, 1933 in Vilna - Wilno, Poland (now Vilnius, Lithuania), Bak was recognized from an early age as possessing extraordinary artistic talent. He describes his family as "secular, but proud of their Jewish identity." Immediately following the German invasion of Poland in September 1939, Vilna and the whole East of Poland was attacked by the USSR. After one month though, the Soviets retreated, giving back the city to the Republic of Lithuania. An estimated 50,000 Jews found refuge in the city.
As Vilna came under German occupation on June 24, 1941,
Bak and his family had to move into the Vilna Ghetto.
At the age of nine, he had his first exhibition inside the ghetto, even as massive executions and murders perpetrated by the Nazis and their Lithuanian collaborators
took place almost every day.
Bak and his mother escaped the destruction of the
Vilna Ghetto by seeking refuge in a Benedictine convent.
They were helped by a Catholic nun named Maria Mikulska.
From the convent they had to flee back to the Vilna ghetto,
and were then deported to a forced labour camp,
and found refuge again in the convent where they
remained in hiding until the end of the war.
By the end of the war, Samuel and his mother were the only members of his extensive family to survive. His father, Jonas, was shot by the Germans in July 1944, only a few days before Samuel's own liberation. As Bak described the situation, "when in 1944 the Soviets liberated us, we were two among two hundred of Vilna's survivors--from a community that had counted 70 or 80 thousand." Bak and his mother as pre-war Polish citizens were allowed to leave Soviet-occupied Vilna and travel to central Poland, at first settling briefly in Łódź. They soon left Poland for good and traveled into the American occupied zone of Germany. From 1945 to 1948, he and his mother lived in Displaced Persons camps in Germany.
He spent most of this period at the Landsberg am Lech DP camp in Germany.
It was there he painted a self-portrait shortly before repudiating his Bar Mitzvah ceremony.
Bak also studied painting in Munich during this period,
and painted "A Mother and Son", 1947,
which evokes some of his dark memories of the Holocaust and escape from Soviet-occupied Poland.
In 1948, he and his mother immigrated to Israel,
and four years later he studied art at the Bezalel Academy of Arts and Design in Jerusalem.
Bak spent most of his time in Israel studying and living in a modest flat in Tel Aviv and did not paint very much during that period. He continued his studies in Paris,
and then lived in Rome, in Israel, in Switzerland and then moved to the U.S.A.