Natural disasters in China divine retribution: "tianzai" (天災), literally 'heavenly disaster'. In ancient beliefs, natural disasters were seen as Heaven’s response to immoral human behaviour, whereby the conduct of different individuals carried different weights. While the behaviour of common people ranked last, the actions of bureaucrats had a greater effect. Given that in Imperial China the emperor's behaviour was believed to be the most important, popular belief was that the emperor should attempt to prevent disasters by ensuring his conduct was in following with moral codes – and if a disaster should occur, he was responsible for addressing the consequences. According to the Overseas
What Is and What Should Never Be 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. The rhythm of the vocals is almost like a rap. It's insane — one of their most psychedelic songs." This was also one of the first songs recorded by the band for which Robert Plant received writing credit. According to rock journalist Stephen Davis, the author of the Led Zeppelin biography "Hammer of the Gods: The Led Zeppelin Saga", the lyrics for this song reflect a romance Plant had with his wife's younger sister. "What Is