What does the brother realize about Sonny as he plays the piano? What does the music allow Sonny to do?

Throughout Sonny's life, he has been searching for a way to escape reality, avoid the lows, to not suffer. This journey took him through some tough times. It began with Sonny enlisting in the army at a young age. Then came the addiction to heroin. It allowed him to put all his worries behind and live in a world where there was no suffering. As Sonny was playing the piano, his brother noticed him coming alive. Up on stage, Sonny was at peace with himself and his surroundings. He experienced so much suffering and through his music, Sonny was able to finally release. This was how he could cope with reality; to deal with those past sufferings and hardships. Sonny expressed his feelings in a way he had never done before by playing the piano. It was his truest form of expression. He used music as a way to deal with reality opposed to him using heroin to escape it. This is key because it shows a turning point for him. He could've continued abusing drugs, but he chose to face the enemy head on. Sonny's music even affected the audience. It helped those people to relax and release just as he was able to do.