In honor of the 40th anniversary of Prince’s self-titled second album, “Prince” — which was released on October 19, 1979 — late artist’s estate and Warner Records have released a previously uncirculated, solo acoustic demo recording of his song “I Feel for You,” available on streaming services and as a limited-run 7” vinyl single.

The demo features a 20-year-old Prince running through the song, accompanying himself on acoustic guitar. It is roughly recorded — you can hear the cassette recorder being turned on — but stunning. The recording was created in the winter of 1978-1979, around the time Prince was preparing to make his solo debut at the Capri Theater in North Minneapolis, and it was recently rediscovered on one of the countless cassette tapes stored in his much-vaunted vault of previously unreleased recordings.

“I was blown away,” says Prince vault archivist Michael Howe. “Here is 20-year-old Prince thinking aloud, feeling his way through the song. You hear his incredible talent shining through on acoustic guitar, which is not something he typically showcased, and his guide vocal is astonishingly great.”

“I Feel for You” was originally released on “Prince,” but at the height of “Purple Rain” mania five years later, the song was made into a two-Grammy-winning global smash by Chaka Khan.

The new two-track single includes the acoustic demo of “I Feel for You” on the A-side and the original studio recording on the B-side, and is available as a Made to Order release exclusively at Prince.com for the next seven days.

The release is part of an ongoing campaign by the estate to release material from Prince’s sprawling vault. Previous releases include the 2017 “Purple Rain” deluxe edition, the “Piano & a Microphone 1983” and “Originals” albums, and coming next month, a four-CD collection of material recorded during the “1999” sessions.