What Is and What Should Never Be - Live on Tasty Pop Sundae from BBC Sessions;Remaster

This very dynamic song alternates between hushed verses and an explosive chorus as Robert Plant sings about whisking a fair maiden to castle where they will join together as one. According to the book Hammer of the Gods: The Led Zeppelin Saga, he wrote the lyric reflecting on his affair with his wife's younger sister.

The production makes liberal use of stereo as the guitars pan back and forth between channels. The vocals were phased during Robert Plant's screaming part.

This was one of Plant's first songs recorded by the band, and also marks the first appearance of drummer John Bonham's Chinese gong, which he set up as part of his drum kit in concerts. The gong appears in the middle part among Jimmy Page's guitar riffs.