Elton John says Prince walked out on him twice - once at a party and once onstage - before they finally performed a complete song together.

The British legend shares the story in a foreword he wrote for Duane Tudahi's new book Prince and the Parade and Sign O' the Times Era Studio Sessions: 1985 and 1986, an excellent and detailed document of one of the most fruitful eras of Prince's career.

"This book covers part of Prince's great moment, when he was writing one incredible song after another," John notes. "Every major artist has one, the period when they're on a roll, where they can't seem to do anything wrong. But Prince's great moment seems slightly inexplicable and unearthly too, even more so when you read about it in the kind of detail contained here."

You can read an exclusive excerpt from John's foreword below, and also watch what happened when the two superstars finally teamed up to perform the Beatles' "The Long and Winding Road" on Sept. 13, 2007.

The first time I met Prince was at a party after the Grammys in a restaurant in L.A. He was standing alone by a wall, so I went up and introduced myself to him: "Hi, my name's Elton and I'm a huge fan of yours and I just wanted to say ... ." That was as far as I got - Prince just walked off without a word. As you can imagine, that was quite a deflating experience, but I knew how shy he was - everyone knew how shy Prince was - and I loved his music so much that a few years later I tried again. I went backstage when he was playing his residency at the Rio in Las Vegas, and I was doing the same at Caesars Palace. He'd got the hotel to build him his own nightclub, Club 3121, everything painted purple, and I'd see him driving around town in a Bentley on which the paintwork turned purple when the sun hit it. This time, he asked me to play onstage with him that night. He wanted me to sing the Beatles' "The Long and Winding Road." I told him I didn't know the words. He said that he didn't either, and that he had them written out on the floor of the stage. So I went onstage with him, and we started playing "The Long and Winding Road." It's sounding great. Midway through the song, I looked around. No Prince: he'd just walked off again.

...

I got to play with him one more time, in London at the 02 during his 21 Nights in London residency. He asked if I'd play "The Long and Winding Road" again, and this time he stayed onstage throughout. It was a real thrill - as exciting as playing with John Lennon, or Bob Dylan, or Ray Charles - but then, watching Prince perform that night from the audience was just as thrilling. It was one of the greatest performances I've ever seen in my life. When he passed away, I said that we all knelt at Prince's feet, and I meant it. I like to think that if you're a real musician you recognize quality when you see it, but you didn't need to be a musician to recognize that in Prince you had quality that was extraordinarily high. You just needed ears and eyes.

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