Harry Potter and the Prisoner of Azkaban (Harry Potter, #3)

by J.K. Rowling

“You think the dead we have loved ever truly leave us? You think that we don’t recall them more clearly than ever in times of great trouble? Your father is alive in you, Harry, and shows himself most plainly when you have need of him. How else could you produce that particular Patronus? Prongs rode again last night.”