For Joni Mitchell’s 70th birthday, here’s a clip of her singing “Chelsea Morning” on “The Dick Cavett Show.” This was her first big national TV appearance, on August 19, 1969.

Bill and Hillary Clinton loved that song so much that they named their only daughter Chelsea. Another big fan was Grace Slick, seen on Cavett’s left after her band, Jefferson Airplane, also performed on the show. After Mitchell’s performance, Slick led a standing ovation for her.

Because doing the Cavett show that night was so important to her career, Mitchell’s managers advised her not to go with Crosby Stills Nash & Young to another gig that weekend — Woodstock. The irony is that a vast majority of people think she did perform there because she wrote a tremendously popular song about it.

In his autobiography, “Wild Tales,” Graham Nash (who was then living with Joni), explains:

When we got back to New York City, Joni was waiting for us at our hotel, not at all happy that she’d missed the festival. Frustrated, she’d watched the whole thing unspool on TV news, which had covered it practically from beginning to end. Our babbling and rambling about the experience didn’t make it any easier for her. Instead she’d put all her energy into writing about it and had a good 90% of the song finished before we arrived. She played it for us before we even got settled.

I came upon a child of God
He was walking along the road…

It was a beautiful, gentle ballad, rather smoky, folky and moody. I noticed Stephen listening intently with that strange look in his eyes. When Joni had finished, after delivering that magical refrain — We are stardust, we are golden — he didn’t hesitate. “Can we have that song?” he asked her. “I know exactly what to do with it. But I’d like to change it a little.”

Because Joni was one of the lads, to say nothing of being my girlfriend, she merely shrugged and said, “Sure.” And of course, Stephen turned her ballad into a balls-out rock ‘n’ roll song. He took that songbird, dark-purply approach of hers and attached electric jumper cables to it, with Neil adding that killer of a riff at the top.