Flashback: Watch Glen Campbell Duet With 'Gentle on My Mind' Songwriter

Inspired by a classic Sixties film, the John Hartford best-seller was a radio hit and TV theme song

Glen Campbell recorded "Gentle on My Mind" 50 years ago today, May 17, 1967.

Although he had been a vital part of the Los Angeles recording scene in the early Sixties, as one of the session musicians in the collective known as the Wrecking Crew, Glen Campbell would, of course, go on to exemplify the label of multi-faceted entertainer, dominating the country, pop and easy listening charts, hosting his own weekly network variety series, appearing in movies and playing throughout the world.

In many ways, the road to Campbell's exceptional solo career began in earnest 50 years ago today, on May 17th, 1967, when the Arkansas-born instrumentalist and vocalist stepped into the recording studio to lay down the tracks for "Gentle on My Mind." A rolling, poetic tune penned by banjo player John Hartford, the song, the writer would explain later, was inspired by the film Doctor Zhivago, the sweeping romantic epic that hit cinemas in 1965, starring Omar Sharif and Julie Christie. Hartford would tell Cincinnati magazine writer and bluegrass musician Katie Laur that he was constantly writing songs at the time and that the memorable first line of the song, "It's knowing that your door is always open and your path is free to walk," was written while seeing Christie's face in front of him. Later, while on a plane flight shared with the actress, he sent her a note telling her about writing the song, after which she invited him to sit with her. "After about 15 minutes of talking to her I was so disillusioned," he said. "I kept thinking why did I do this?"

Although not one of Campbell's biggest chart hits, the tune helped him break through at country and pop radio, earning two Grammy award each for the performer and the song's writer. Hundreds of subsequent recordings made it the decade's most popular record, behind Paul McCartney's Beatles classic, "Yesterday."

When Campbell began hosting the CBS variety series, the Glen Campbell Goodtime Hour, in 1969, Hartford's song served as the series' theme tune and the musician, who played fiddle and banjo, was featured on the show regularly. In late February 1968, Campbell and Hartford, who were frequent participants in music-comedy duo the Smothers Brothers' variety series, taped a performance of the song just ahead of the Grammy Awards, where the song received a total of six nominations. Just a few months later, Campbell's network series would serve as a summer replacement for the Smothers Brothers and debut on its own in January 1969, running until June 1972. "Gentle on My Mind" would be re-released, following Campbell's summer series and the breakthrough smash, "By the Time I Get to Phoenix," which was the first of numerous songs the singer would record penned by Jimmy Webb. Requests for the pair to perform the song in its entirety led to this one on the Goodtime Hour.

In 1988, the pair would perform it again on the briefly revived Smothers Brothers Comedy Hour. Most recently, the song has been covered by the Band Perry and is featured on Alison Krauss's solo LP Windy City.