In what year was Robert M. Pirsig's most famous book first published?
Robert M. Pirsig: Robert Maynard Pirsig (September 6, 1928 – April 24, 2017) was an American writer and philosopher. Robert M. Pirsig:  He was the author of the philosophical novels "Zen and the Art of Motorcycle Maintenance: An Inquiry into Values" (1974) and "" (1991).
i don't know