( By year’s end, the Beatles and their ingenious producer, George Martin—who died at age 90 on March 8—had transformed this folk-like tune into “Strawberry Fields Forever,” a recording (released in 1967) that many critics regard as one of rock’s most enduring masterpieces, a rich-textured, dark-hued four-minute essay in musical and lyrical psychedelia that both captures and transcends its time.

Lennon’s earliest recordings of the song, from Almería, begin not with the laconic refrain that opens the finished recording—“Let me take you down / ’cause I’m going to Strawberry Fields / Nothing is real / And nothing to get hung about”—but with a verse that starts, “No one I think is in my tree.” Lennon never explained this puzzling first line, but it may refer to his feeling of isolation during the backlash surrounding a comment he made earlier that year about the Beatles being “more popular than Jesus.”

The eventual song-opening refrain, completed before Lennon left Spain on Nov. 6, was a brilliant touch. For listeners not obsessed with the Beatles’ biographies, “strawberry fields” is simply colorful, evocative imagery. But for Lennon, it was a nostalgic reference to Strawberry Field, an orphanage near his childhood home that evoked an innocent time before the madness of Beatlemania...

“Even ‘Strawberry Fields’?” Mr. Martin asked.

“Especially ‘Strawberry Fields,’” Lennon said. )