What is the author's tone in On Becoming a Novelist by John Gardner?

The tone of John Gardner's On Becoming a Novelist is lighthearted and upbeat. He writes specifically for young people intent on becoming serious novelists, answering the questions he is typically asked after lectures and during writers' workshops. He consistently describes his own experiences of writing and teaching about writing, but backs off from claiming any element might be typical of all writers. He is, thus, as objective as wide experience allows, but necessarily subjective, because he has limited primary experience.