Of all the songs recorded for the White Album, "Blackbird" dates back the furthest. The seeds were sewn in the late Fifties when a 16-year-old McCartney learned the introduction of Bach's "Bourree in E Minor" on guitar in a somewhat misguided effort to impress girls. "You often did things just as party pieces, things to show off, literally, at a party," McCartney recalled during a seminar at Rollins College in 2014. "You know, 'Hey girls ...' You would do that. Unfortunately, none of them bothered." The budding musician's rudimentary classical guitar skills rendered the rest of the movement prohibitively difficult, so he improvised an abbreviated ending – one he never forgot. "Part of its structure is a particular harmonic thing between the melody and the bass line which intrigued me," he explained to Barry Miles.
McCartney expanded on the guitar figure while visiting his Scottish farm shortly after returning from India in the spring of 1968. "I developed the melody on guitar based on the Bach piece and took it somewhere else, took it to another level, then I just fitted words to it," he told Miles. "I had in mind a black woman, rather than a bird. Those were the days of the civil rights movement, which all of us cared passionately about, so this was really a song from me to a black woman, experiencing these problems in the States."
The words were fully in place by the time he debuted the song at Kinfauns, but the musical structure needed work. The opening line is played only once, rather than repeated, and the wordless mid-song guitar wind-down present on the White Album is absent. But given the stripped down nature of the final recorded version, the demo sounds fairly similar. The demo is primarily a solo venture, but McCartney's double-tracked vocals and acoustic guitar picking get some help from Lennon, who enthusiastically contributes bird sounds.