The added workload involved with launching their own record label, their always-grueling tour schedule and their superhuman appetites for all manner of rock-star excess finally started catching up to Led Zeppelin as the ‘70s hit the halfway mark. Even the relatively reserved John Paul Jones almost quit the group to become choirmaster of Winchester Cathedral around then.

But he was lured back to the band, which began banging together new material in early 1974. They then folded in an assortment of leftover recordings from earlier albums that dated all the way back to 1970. The result would be Zep's double-record classic ‘Physical Graffiti.’

The newer material (including ‘In the Light,’ ‘Ten Years Gone,’ ‘In My Time of Dying’ and the monolithic ‘Kashmir’) tends to eclipse some of the older outtakes, but the unparalleled depth and breadth of songwriting makes a strong case for ‘Physical Graffiti’ being Zeppelin’s magnum opus.

Whatever the case, this incredible outpouring of musical ideas remains one of the most ambitious and awe-inspiring albums of the classic-rock era.

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