March 15, 2016 10:32 AM EDT

J.K. Rowling took to Twitter to respond to a moving letter from the mother of one of her fans. In the letter, which actress Carey Mulligan read aloud at a London event called Letters Live on Sunday, mother Chrissy Hart writes that the Harry Potter books helped her child deal with a cancer diagnosis.

“Your words built a castle for her to move into when the prognosis got worse,” the letter reads. “Mrs. Rowling, cancer threatened to take everything from my daughter, and your books turned out to be the fortress we so desperately needed to hide in.” The young child died last week of cancer.

“I think I wanted to write because words were always my safe place,” Rowling tweeted in response. “I only wish words could bring her back to you.”

Read the mother’s full letter below:



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