J.K. Rowling attends the Lumos fundraising event in 2013. Credit: David M. Benett/Getty Images

A mother of a young, deceased cancer patient penned a heart-wrenching letter to J.K. Rowling, detailing how the Harry Potter series created a “fortress we so desperately needed to hide in.”

The poignant thank you note written by Chrissy Hart, was read by Pride and Prejudice and Zombies actress Ellie Bamber on March 10 at Letters Live, an event in London during which celebrities read remarkable missives out loud. Benedict Cumberbatch, Jude Law and Carey Mulligan also took part. 

“You taught her that for every chemo she has to go through, there will be the opportunity to fly across a lake on a hippogriff. For every time her heart seizes with fear of pain, there will be me chasing it away with a Patronus charm,” wrote Hart, whose daughter passed away last week. “Your words built a castle for her to move into when the prognosis got worse.”

She also thanked the British scribe for providing her with courage as she watched her daughter die.

“You made me realize that a mother’s courage might come in the form of her tears,” she wrote. “I might not have the physical ability to block her from what will take her away from me, but I can be loving and gentle like Molly, stoic in my affection like Minerva, protective and loyal like Hermione, and waiting to welcome her home like Lily. “

She continued: “For every child that is taken too early, people will come together, huddling close in a big group, wands held high to light the dark sky with the love they felt. You built Hogwarts as a home for her to return to. And for me.”

Hart’s letter went viral when Star Wars: The Force Awakens star Daisy Ridley posted an excerpt to her Instagram, captioning it “one of the most beautiful letters I’ve ever read.”