It was written by Jimmy Page and Robert Plant and was included as the second track on Led Zeppelin II (1969).
Guitarist Jimmy Page has said that he wrote the song on an acoustic Harmony Sovereign H1260 guitar.
Record producer Rick Rubin has remarked, "The descending riff [of "What Is and What Should Never Be"] is amazing: It's like a bow is being drawn back, and then it releases.
[5] According to Jean-Michel Guesdon and Philippe Margotin:[1] "What Is and What Should Never Be" was performed live at Led Zeppelin concerts between 1969 and 1973.
A live version taken from a performance at the Royal Albert Hall in 1970 can be seen on the Led Zeppelin DVD.