Pumpernickel an old Bavarian term for "hard", either referring to the process used to grind the grain into flour, or the density of the final bread product. According to "Langenscheidts Taschen Wörterbücher" (1956), it refers to a form of "pumping work". The philologist Johann Christoph Adelung states that the word has an origin in the Germanic vernacular where was a New High German synonym for being flatulent, and was a form of the name Nicholas, commonly associated with a goblin or devil (e.g. "Old Nick", a familiar name for Satan), or more generally for a malevolent spirit or demon. Hence, "pumpernickel"
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