John Hartford remains best known for the country-pop standard "Gentle on My Mind," a major hit for Glen Campbell and subsequently covered by vocalists ranging from Frank Sinatra to Aretha Franklin. The song remains among the most often recorded in the history of popular music, its copyright netting Hartford well over a hundred thousand dollars annually for many years. But there was more to Hartford than that curious mix of highly literary folk music and MOR romantic nostalgia, told from the perspective of a homeless man remembering days of perfect love. Hartford was a multi-ta...