John Locke has a new article out, although he died in 1704. When England’s King Charles II discovered a failed 1683 assassination plot against himself and his brother, he beheaded the plotters and started arresting opponents. Among the targets was Locke, who knew some of the conspirators but likely wasn’t involved. Fearing for his life, Locke fled to the Netherlands. Before leaving, he deposited several manuscripts with Edward Clarke, a member of Parliament and trusted friend.

One of those manuscripts has only now been discovered—in the Annapolis, Md., library of St. John’s College. This month it was published for the first time, in the Cambridge Historical Journal, by independent scholar J.C. Walmsley and Cambridge University fellow Felix Waldmann.

The title of the work, written in 1667 or 1668, is “Reasons for Tolerateing Papists Equally with Others.” Mr. Walmsley tells me that when he came across the title in a 1928 book catalog, it seemed “very unlikely that this was actually a real thing that Locke had actually written.” In one of Locke’s most famous works—the 1689 “Letter Concerning Toleration,” which helped shape the First Amendment to the U.S. Constitution—he had taken a liberal view of religious tolerance for Protestant sects persecuted by the Anglican Church, but excluded Catholics and atheists.