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Applying artificial intelligence to the printing press during the Protestant Reformation

Friday, 28 July, 2023

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Dr Drew Thomas is a Science Foundation Ireland and Irish Research Council Pathway Fellow at the University College Dublin School of History. He is leading the project, "Applying Artificial Intelligence to the Printing Press: Transforming Visual Communication During the Protestant Reformation".

It was provocative by any standard. But when German religious reformer Martin Luther (1483 - 1546) published the richly illustrated, pope-mocking pamphlet,The Passion of Christ and Antichristin 1521, the Catholic Church was all-powerful in western Europe and heretics were burned at the stake. 

“It had illustrations depicting the Passion of Christ, but it would put them side by side with illustrations featuring the pope doing the exact opposite,” explains Thomas, of the notorious book published four years after Luther’s 95 Theses attacked the sale of indulgences in the Catholic Church and led to the father of Protestantism’s excommunication.

“For example, it shows Jesus washing the feet of the apostles. Next to it, it shows the pope forcing kings and noblemen to kiss his feet. It shows an illustration of Jesus pushing the money changers out of the temple; it shows a picture of the pope selling indulgences in the church,” he adds, of the buying of forgiveness for sins. “It shows an illustration of Jesus ascending to heaven and an illustration of the pope descending to hell. So you can see how crazy and really provocative this was and that it would have made a lot of people very angry. But it would have made other people laugh, especially if you’re showing this in the pub.”

Most people in the mid-sixteenth century didn’t read, but, of course, “if you see those illustrations next to each other, you can understand what's happening”. 

Luther only avoided being burned at the stake thanks to the protection of his Noble Overlord, the Elector of Saxony. Meanwhile his religious beliefs spread like wildfire, because of the invention of the printing press around 1450. 

“There's a famous history thesis that says without the printing press, there would have been no Reformation. And Luther highly benefited from the printing press spreading his message.” 

Reformation-era imagery was particularly powerful and persuasive - and remains a source of fascination for Thomas, though he is “not really sure” why he was first drawn to it. 

“I had a really good history teacher in secondary school and that inspired me. I grew up Protestant but I went to a Catholic school so I always wondered if that somehow influences my interest in the differences and similarities between Catholics and Protestants.”

In his latest research project, Thomas will use artificial intelligence to study how both religions used images, illustrations and visual communication during the Protestant Reformation. 

“We’re quite interested in how each party used illustrations not only in their educational materials, because they would want to provide support to their believers, but also in their propaganda and political literature attacking each other.”

For instance, he is curious about whether papal imagery will be more common in Protestant illustrations because they are making fun of the pope - or in Catholic illustrations because the pontiff became such a touchstone for their identity. 

In order to study book illustrations “the first thing you need is a list of books with illustrations”. Thomas has already compiled such a list via the Ornamento Project, which he previously undertook with his colleague Professor Alexander Wilkinson in UCD School of History. They applied 70 million pages to the supercomputer Kay at the Irish Centre of High-End Computing, which resulted in 5.6m images documenting book ornamentation from the invention of the press around 1450 up to 1600. 

“Now I'm using a part of that Ornamento Project as a corpus for this project, looking at how Protestants and Catholics used images and religious illustrations. I'm still in the early stages of limiting the corpus. We're slowly creating these image training datasets that we can apply to the AI to identify images.”

He disputes the common misperception that AI “does all the work for you” in these types of projects. The reality for Thomas is spending hours scrolling through tens of thousands of images on his laptop, curating relevant training datasets. He needs these trained images in order to teach the AI to find patterns and identify, for instance, “all the illustrations with people or with saints or with bishops”.

He adds: “It’s helpful that we create these training datasets which can be used for other projects so they don't have to do the manual labour of creating their own training datasets.”

Thomas also wonders whether the exact same illustrations were used in both Catholic and Protestant books, “so maybe they don’t have different iconographies”. But with some cities, such as Cologne, being very Catholic, it is also possible that the two religions developed individual iconographic identities. 

“We will find that out,” he says. 

AI is also helpful at pinpointing counterfeits. Martin Luther’s work, created before copyright was invented, was widely plagiarised.  

“If I see an illustration in one book that says it was printed in Wittenberg, the home of Luther’s movement, but with AI, I can match that to instances used in five other books that were all printed, say, in Augsburg, I can be pretty confident that the Wittenberg book with that illustration is actually counterfeit having been produced in Augsburg. So I use AI to help identify counterfeits.”

Despite these forgeries, the printing press - which was every bit as revolutionary as the internet age - greatly reduced the margin for error of copying works by hand. 

“So there was some permanence to that, where maybe with the modern internet age there is a rise in fake news and deep fake videos. I really wonder what it will be like when we can no longer trust the videos we see.”

Listen to the(opens in a new window)podcast.

This article was originally published on 8 November 2022.