Banjo Paterson had two children, Grace (born in 1904) and Hugh (born in 1906). Paterson had been previously engaged to Sarah Riley for eight years, but this was abruptly called off in 1895 following a visit to her at Dagworth Station in Queensland where she was visiting the Macpherson family. It was here that Paterson met his fiancée's best friend from school days, Christina Macpherson, who composed the music for which he then wrote the lyrics of the famous "Waltzing Matilda". However, following this collaboration Paterson was suddenly asked to leave the property, leading historians to conclude that he was a womanizer
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