2018 marks 21 years since the firstHarry Potterbook was published, but it seems that J.K. Rowling continues to be humbled and astonished by her incredible success.

The author posted a photo on Twitter this week of a note she discovered when she was in a second hand book store, which reminded her of how popular and significant her books have been to her fans:

Second hand bookstores are always full of surprises but I did not see this one coming. pic.twitter.com/1cWDRABdvL

— J.K. Rowling (@jk_rowling) July 23, 2018

In a section of the store, Rowling found a shelf of books, that was labelled, not as simply fiction or non-fiction, romance or biography, but in a pleasantly surprising way. The label said, “Books you need to buy so you can say ‘I should read that next’ before re-reading Harry Potter.”

Taking the wording of the classification of those books as the huge compliment it was, Rowling tweeted a photo of it, with the caption:

“Second hand bookstores are always full of surprises but I did not see this one coming.”

The author, who is one of the most successful writers of all-time, may have been surprised by her discovery, but her fans were not. They tweeted their support in response, letting Rowling know how important she, and her work, is to them.

One fan said, “Surely by now you should know we’re still madly in love with your books. They inspired a generation of readers, and they continue to inspire us. They’re part of who we are.”

Whenever I get into Trump overload, HP saves me. Third go round since election.

— Rebecca Williams (@JustToday1944) July 23, 2018

Here is my homage to Sorcerer’s Stone Chapters 5, 6, and 7. My basement remodel – it’s work in progress, but it’s getting there! pic.twitter.com/1ahwheQIfw

— KathleenMollyWeasley (@MollyPrewett7) July 23, 2018

Amongst the almost 7000 re-tweets and 63 000 likes, this Twitter user spoke for everyone when she posted, “Re-reading Harry Potter after all of this time?” with a GIF of Professor Snape saying, “Always.”

Re-reading Harry Potter after all this time? pic.twitter.com/k0oga51FPG

— Ilenia Manzo (@IleniaManzo) July 23, 2018