What is the theme in Cash: The Autobiography by Johnny Cash?

Love of music is a main theme. Johnny Cash's earliest memories are tied up in his family and largely in his mother's singing. From then, Johnny is enamored with music and loves to hear anyone sing. He recalls when his family finally got a radio and says that it was then the biggest treat of all when a sudden rainstorm would chase the family in from their work in the fields so that Johnny would have free hours to listen to the music on the radio. John is also excited to learn that a young boy in the neighborhood, Pete Barnhill, has a guitar. While the other children are making fun of Pete because he is crippled from a case of polio, Johnny spends many happy hours with his young friend, listening to his music.