A manuscript by 17th-century British philosopher John Locke has been discovered in the archives of St. John’s College library in Annapolis, shedding light on how the man credited with the concept of separating church and state first started to tinker with the notion of religious tolerance.

It the first major discovery of his work in a generation.

The document titled “Reasons for tolerating Papists equally with others” is composed of two lists: the reasons people should tolerate Catholics — and reasons they should not.

“It is like the significant chapter of understanding his views,” said Craig Walmsley, who found the papers and is an editor for Clarendon Edition of the Works of John Locke. “It shows him starting a tolerant outlook, which is really interesting. It reveals his nuanced views on the tolerance of Catholics.”

It’s also an unusual find in one of the nation’s oldest colleges in a state with deep Catholic roots.

Locke had a deep influence on Western thinking, specifically classical liberalism and the republic-style of government. His notion of individual rights is believed to inform the Declaration of Independence.

It was 2015 when Walmsley began searching for undiscovered works by Locke. He reached out to the Greenfield Library on St. John’s Annapolis campus after months of searching online where he found what he called an “obscure reference” in a 1920s book catalog.

“Tracking down that reference took me months before I came across that particular page, and then I was exceptionally fortunate that St. John’s catalog was digital,” Walmsley said. “It was a lot of gumshoeing and a little bit of luck.”

Walmsley was inspired to search for Locke’s work because another Locke scholar, Felix Waldmann, also discovered books that had been part of Locke’s personal library.

The manuscript found at St. John’s is dated from 1667 to 1668 and is connected to another Locke essay, “Essay Concerning Toleration,” as it provides additional context for Locke’s view on religious tolerance.

According to Walmsley, the manuscript has changed hands many times. It was owned by a descendant of a Locke friend until 1920, sold to a book dealer and sold again. It landed in a private collection. It was later donated to the college, becoming another item in the college’s rare book room, said Cathy Dixon, the library director.

After finding the copy through the digital catalog, Walmsley sought to confirm it with library officials.

“He wanted to take a look at it,” Dixon said. “It is in our rare book room, so we scanned it and sent him a copy and he recognized the handwriting.”

Walmsley also noted that the manuscript had not been quoted by others before.

He then traveled to Annapolis to inspect the document in person.

Together, Walmsley and Waldmann wrote an article on the manuscript and published it in August in The Historical Journal of Cambridge University Press.

Along with the new discovery, the manuscript is currently recognized as the first piece of evidence that Locke, a Protestant, tolerated Catholics at a time of deep strife between the branches of Christianity and his theory on toleration, Waldmann said.

“It is important to emphasize the manuscript. Part of it defends the toleration, but the other part is adamantly against the tolerance,” Waldmann said. “The question we address in the article is what this manuscript might mean in the development of toleration.”

But overall, the rarity of this discovery is significant, he said.

“Perhaps the most important thing to emphasize is that manuscripts like this are extraordinarily rare,” Waldmann said. “Scholars have been searching for manuscripts like this for decades.”

The discovery also can shape future studies of Locke and how his theories are taught, he said. It can provide greater understanding of Locke’s views and his arguments.

“It gives you a better insight into the arguments because you can see the purpose of what he was arguing,” Walmsley said.