The new Kanye West single contains a blast from Paul McCartney's past, delivered by none other than the former Beatle himself.

Continuing a recent series of collaborations that's seen McCartney chip in on West's "Only One" and "FourFiveSeconds" singles (and which brought McCartney his biggest hit in years along the way), the duo worked together on "All Day," the latest release from West's upcoming So Help Me God LP, and the results may trigger a jolt of recognition among longtime fans familiar with Sir Paul's older unreleased material.

As pointed out by Rolling Stone, McCartney can first be heard toward the end of "All Day," when the song veers out of its established arrangement and into a gentler section led by acoustic guitar and whistling. This bit seems to be a new recording of a song McCartney first worked on in 1969, when — as he explained in an interview — he was inspired by a Picasso painting to try writing a song using only two-fingered chords on the guitar.

That composition, while never released, later morphed into "When the Wind Is Blowing," a track that was worked on and ultimately discarded during the sessions for 1971's Ram LP. Its peaceful, bucolic mood would seem to be at odds with a song whose lyrics include lines like "Ball so hard, man, this s--- cray," but then again, many would have said the idea of McCartney and West working together didn't make sense either.

A number of unofficial "All Day" uploads have come and gone since the studio version's release yesterday, but it seems likely to surface on West's Vevo video page soon. In the meantime, the single is now available for purchase.

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