A long letter that is said to have inspired Jack Kerouac’s masterpiece On The Road is heading to the auction block after it was discovered, 60 years after it went missing.

The 16,000-word letter was written by Neal Cassady, a fellow member of the Beat Generation. It was written in a stream-of-consciousness style, which inspired Kerouac to scrap a draft of On The Road. He re-wrote the novel to follow Cassady’s style and the book has gone on to be one of the major pieces of American literature.

Kerouac believed that Cassady could have become a major figure in literature himself, had the letter not gone missing. As The Independent points out, Allen Ginsberg was believed to be responsible for losing the letter.

However, Ginsburg had actually tried to get it published in San Francisco, but the small publishing house Golden Goose Press never opened it before it went out of business. While the owner intended to throw out his unopened letters, the owner of an indie music label next door saved the publisher’s papers.

Los Angeles performance artist Jean Spinosa told The Associated Press that she found the letter two years ago, while cleaning out her late father’s house.

The letter is known as the “Joan Anderson Letter,” in reference to the girl Cassady writes about.

Joe Maddalena’s Profiles in History auction house will be auctioning off the letter on Dec. 17. He hasn’t set an estimate for the letter, but an original On The Road manuscript sold for $2.4 million in 2001.