The nunnery at Palma di Montechiaro, Sicily.
The nunnery at Palma di Montechiaro, Sicily. Archenzo/CC BY-SA 3.0

In 1676, Sister Maria Crocifissa della Concezione had an infernal conversation with the Devil. When she came to her senses, the nun, who lived at a convent in Palma di Montechiaro in Sicily, found she had written letters in an indecipherable language. She and her sisters believed the letters were the work of Satan, who had tried to turn her away from God.

One of the letters survived, but more than three centuries later, its contents were still a mystery. But in August, the LUDUM science museum in Sicily obtained a copy of it and subjected it to a more modern analysis, using intelligence-grade code-breaking software, The Times reports.

The LUDUM group, led by Daniele Abete, had found the code-breaking software in one of the darker corners of the web, where algorithms developed by intelligence agencies have leaked to a wider audience. After priming the algorithm with ancient Greek, Arabic, and Latin, as well as the Runic alphabet, the team fed it the text of Sister Maria’s “Devil’s letter.”

The strategy worked: The letter turned out to be made of a jumble of languages that, when teased apart, could be read. The nun’s writing indeed has a devilish bent to it. As The Times reports, Sister Maria wrote that the Holy Trinity were “dead weights” and that a basic principle of Catholic doctrine “works for no one.”

Abete suspects that today the nun might be diagnosed with schizophrenia or a similar condition: Perhaps she did hear a voice dictating the letter, and her linguistic skills produced this mishmash of language and heresy.