Led Zeppelin is in court right now fighting a plagiarism charge over "Stairway to Heaven". Members of the band Spirit say its opening cords rip off their song "Taurus".

Robert Plant took the witness stand yesterday and explained how the song was written. It happened more than 45 years ago, when the band was rehearsing and recording at a country estate called Headley Grange.

He was sitting around a fire with Jimmy Page, when Jimmy played him what would become the opening to "Stairway". It turned out Plant already had the beginnings of some lyrics that would go with it.

He even recited them in court: "There's a lady who knows all that glitters is gold and she's buying a stairway to heaven / When she gets there she knows if the stores are all closed, with a word she can get what she came for." From there the song, started, "rolling pretty fast."

Here's the acoustic demo of "Stairway":

One of the issues in the trial is whether Plant saw Spirit perform one night at a club in Birmingham in 1970 and hung out with the band after the show. That's what they claim and that's where Plant's memory gets hazy. Plant said, "I don't have a recollection of almost anyone I've hung out with."