Quotes from book
A Hat Full of Sky

A Hat Full of Sky is a comic fantasy novel by British writer Terry Pratchett, set on the Discworld and written with younger readers in mind. It is labelled a "Story of Discworld" to indicate its status as children's or young adult fiction, unlike most of the books in the Discworld series. First published in 2004, it is set two years after The Wee Free Men, and features an 11-year-old Tiffany Aching.

“If you don't know when to be a human being, you don't know when to be a witch.”
Source: A Hat Full of Sky

“There isn't a way things should be. There's just what happens, and what we do.”
Source: A Hat Full of Sky

“It's still magic even if you know how it's done.”
Variant: It doesn't stop being magic just because you know how it works.
Source: A Hat Full of Sky

“This book had two authors, and they were both the same person.”
Author's note, revised edition (1992).
The Carpet People (1971; 1992)
Source: A Hat Full of Sky