Fable 5.1 Solves the Cyphral Distich, a 370-year-old cipher

Vals AI reports that Anthropic's Claude Fable 5.1 found a decoding rule for the Cyphral Distich, a numerical puzzle at the end of Thomas Urquhart's 1653 book Logopandecteision. The useful result is a procedure readers can check against the text. Each number's position in a cipher line selects the matching numbered paragraph; the number selects a word within that paragraph; the word's initial supplies a letter. The account says this produces a rhyming prayer supporting Charles II.

One position requires treating the two-word Latin expression "hinc inde" as a single counting unit. The report therefore offers a specific, inspectable solution claim, with a stated counting convention, rather than evidence of general superiority at breaking ciphers. It is Vals's own account; the article does not say historians have confirmed it.