At the time, it was just a struggling musician updating his father on recent activities via the mail.

More than 40 years later, as we read today on Letters of Note, a postcard Jimi Hendrix sent to his dad can be considered a historical document due to the guitarist pointing out two developments that are among the most significant events in his solo career.

In early 1966, Hendrix was still best known for his stint as a sideman for the Isley Brothers and Little Richard.

But by that October, Hendrix — who had relocated to London after teaming up with Animals bassist Chas Chandler to be his manager and producer — felt he was making some major strides under his own name. Understandably, Hendrix wanted his family to know, so he sent a postcard from Germany to his father, James Allen Hendrix, back home in Seattle.

"I have my own group," he wrote, "and will have a record out [in] about 2 months named 'Hey Joe' By the Jimi Hendrix EXPERIENCE. … I think things are getting a little better.” The postcard is signed “Your Loving Son Jimi.”

The Hendrix rendition of the often-covered ‘Hey Joe’ did indeed hit the streets in England before 1966 came to a close. The song later appeared on the first Jimi Hendrix Experience album, 1967's 'Are You Experienced.'

'Hey Joe' was among the songs Hendrix, bassist Noel Redding and drummer Mitch Mitchell played in California on June 18, 1967, at the Monterey International Pop Festival, which proved to be their big breakthrough performance in America. During that song, Hendrix thrilled the crowd by using his teeth instead of a pick for the first guitar solo and later held the instrument behind his back for the second solo.