HP Questions Upon Re-reading: Book 1 Chapter 7

House sorting ceremony, the first memorable event for all Hogwarts students. Isn’t it bewildering that no one knows (at least the book did not mention) about its details? It is understandable to keep it a secret verbally to new students for the mysterious feel. But why is it not written in “Hogwarts: A History”? Legend says that the sorting hat once belongs to Godric Griffindor, one of the four founders of Hogwarts. Why is its existence not recorded in the history book that introduces the school despite being passed down for ages? Considering Hermione’s attitude and behaviour, she must have tried her best to find out the truth of sorting ceremony but her action of memorizing spells suggested that she did not discover the truth as well.