The author of a book that became an unexpected bestseller and virtually defined an era has died. The AP reports that Robert M. Pirsig, whose novel “Zen and the Art of Motorcycle Maintenance” became a million-selling classic after being rejected by more than 100 publishers, died today at his home in South Benwick, Maine.

Pirsig, 88, had been in failing health. His publisher, William Morrow, announced his death.

“‘Zen and the Art of Motorcycle Maintenance’ was published in 1974 and was based on a motorcycle trip Pirsig took in the late 1960s with his 12-year-old son, Chris,” the AP reports. “The book’s path to the best-seller list was long and unlikely. It began as an essay he wrote after he and Chris rode from Minnesota to the Dakotas and grew to a manuscript of hundreds of thousands of words. After the entire industry seemed to shun it, William Morrow took on the book, with editor James Landis writing at the time that he found it ‘brilliant beyond belief.'”

The report adds: “Pirsig’s book ideally suited a generation’s yearning for the open road, a quest for knowledge and skepticism of modern values, while also telling a personal story about a father and son relationship and the author’s struggles with schizophrenia. A world traveler and former philosophy student, Pirsig would blend his life and learning into what he called the Metaphysics of Quality.”

Pirsig later wrote a sequel, “Lila: An Inquiry Into Morals.”

“Chris was killed by a mugger in 1979 and later editions of ‘Zen and the Art of Motorcycle Maintenance’ would include an afterword about him,” the AP notes. “In 2006, the author told The Guardian that his son had not cared for the book.”