Why was Juliek's last performance in Night significant to Eliezer?

When Elie,
Juliek, and so many others arrive at the Gleiwitz concentration camp, they are herded into a
barrack that must have been much too small, as the prisoners collapse in exhaustion on top of
each other - no thought of bunks in that place. Fighting against the crushing weight of those on
top of him, fighting for air to breathe, Elie recognizes the familiar voice of Juliek somewhere
under him. Elie is unable to move so as to relieve the burden of bodies piled on Juliek, but
finds some comfort in knowing that his friend is still alive, even if only barely.

Later, Elie awakens to "the sound of a violin." He can't imagine who could be
playing or why and wonders if he is hallucinating before realizing it is Juliek. In amazement
that Juliek has found a position in which he can play and in awe of what he is hearing, Elie
listens to the music, and to the messages the music conveys.

It was as if Juliek's soul had become his bow. He was playing his life. His whole being
was gliding over the strings. His unfulfilled hopes. His charred past, his extinguished futures.
He played that which he would never play again.

Elie
recognized that, in Juliek's music, he was hearing "my Polish comrade bidding farewell to
an audience of dying men."