Sphagnum also been used to preserve food. Up to 2000-year-old containers of butter or lard have been found. "Sphagnum" moss has also been used for centuries as a dressing for wounds, including through World War I. Since it is absorptive and extremely acidic, it inhibits growth of bacteria and fungi, so it is used for shipping seeds and live plants. Peat moss is used to dispose of the clarified liquid output (effluent) from septic tanks in areas that lack the proper conditions for ordinary disposal means. It is also used as an environmentally friendly alternative to chlorine in swimming pool sanitation.
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