Robert M. Pirsig, whose “Zen and the Art of Motorcycle Maintenance,” a dense and discursive novel of ideas, became an unlikely publishing phenomenon in the mid-1970s and a touchstone in the waning days of the counterculture, died on Monday at his home in South Berwick, Me. He was 88.

His publisher, William Morrow, announced his death, saying his health had been failing. He had been living in Maine for the last 30 years.

Mr. Pirsig was a college writing instructor and freelance technical writer when the novel — its full title was “Zen and the Art of Motorcycle Maintenance: An Inquiry Into Values” — was published in 1974 to critical acclaim and explosive popularity, selling a million copies in its first year and several million more since. (A first novel, it would be followed by only one more, the less successful “Lila: An Inquiry Into Morals,” a kind of sequel, in 1991.)

The novel, with its peculiar but intriguing title, ranged widely in its concerns, contemplating the relationship of humans and machines, madness and the roots of culture.