Jane Austen—homebrewer, musician, and, oh, one of the most famous novelists in the English language—didn’t limit her prose to the fictional world. She was a prolific correspondent, sending missives to friends and relatives (and occasionally soliciting feedback on her work). Some of these were quite playful, as a letter highlighted recently on the Two Nerdy History Girls blog shows.

Austen’s 1817 letter to her young niece, Cassandra Esten Austen, is a bit hard to read even if you are an expert in 19th century handwriting styles. That’s because all the words are spelled backwards. Instead of signing off with “Good bye my dear Cassy,” for instance, Austen wrote “Doog eyb ym raed Yssac.” The letter served as both a New Year’s greeting and a puzzle for the 8-year-old to solve.

The Morgan Library & Museum, MA 1034.6. Photography by Schecter Lee, 2009.

The letter is currently on view at the Morgan Library and Museum in New York City as part of the museum’s "Treasures From the Vault" exhibition, having been donated to the institution in 1975 by a Jane Austen collector and Morgan Library regular named Alberta Burke.

While any of Austen’s communications would be of interest to fans and literary scholars, this one is particularly unique as a historical object. In it, Austen wishes Cassandra a happy new year and writes about a visit she received from six of Cassandra’s cousins the day before, telling her about the cake they ate, feeding robins, Frank’s Latin studies, and Sally’s new green dress.

The Morgan Library & Museum, MA 1034.6. Photography by Schecter Lee, 2009.

“Those simple details give a sense of the texture of Austen’s everyday life—and that she thinks to communicate them to her young niece makes clear that ‘Aunt Jane’ knew just the kinds of tidbits a child of that age would relish,” Christine Nelson, the Morgan’s literary and historic manuscripts curator, tells Mental Floss.

Austen would die just six months later, making it a valuable look at the end of her life. As far as we know, no other backwards-written letters like the one sent to Cassandra have survived in Austen’s archives, according to Nelson, but she says she wouldn’t be surprised if the famous author wrote more. “Given her love of riddles and linguistic games (which comes through, of course, in her novels), I have to believe that other family members were the recipients of similarly playful epistolary gifts,” Nelson says.

If you make it to New York City, you can go decode the letter yourself in person. It will be on display at the Morgan Library until March 11, 2018.

[h/t Two Nerdy History Girls]