The letter
On 20 August 1806 the Abbé Augustin Barruel received a letter in Paris. It was dated the first of that month, sent from Florence, and signed by a man giving his name as Simonini — Jean-Baptiste in the French form, Giovanni Battista in the Italian.
The writer said he had infiltrated the Jewish community of Piedmont and learned what it was planning. His claim was specific and it was new: that the Freemasons and the Illuminati had both been founded by Jews, and that Jews stood behind both with the intention of taking Europe.
Nothing in the letter was true. But as a piece of writing it matters, because it is one of the earliest places where the two halves of a long-running fabrication are welded together. Anti-Masonic conspiracy literature already existed and was politically respectable in counter-revolutionary circles. Antisemitism had a history reaching back many centuries. The Simonini letter proposes that they are one thing, with the Jews as the hidden principal and the lodges as their instrument — the structure that would later be called the Judeo-Masonic conspiracy, and that would be restated a century afterwards in the Protocols of the Elders of Zion.
Why it was sent to Barruel
The letter arrived at a well-chosen address.
In 1797 Barruel had published Memoirs Illustrating the History of Jacobinism, which argued that the French Revolution had not been an upheaval but an operation: the planned work of philosophes, Freemasons and the Bavarian Illuminati acting in concert. The book was enormously influential, and it is the direct ancestor of a great deal of what is still written about the Illuminati today.
What the Memoirs did not contain was Jews. Barruel's conspiracy was a conspiracy of unbelievers and lodges. The letter offered to complete his system by supplying a party standing behind the parties he had already identified — an offer made to the one author in Europe most invested in the architecture it was extending.
The timing was also pointed. Napoleon had convened an assembly of Jewish notables in 1806 to settle the legal standing of Jews in the empire, and the question was being argued publicly. A letter claiming to expose Jewish designs on Europe arrived precisely while the government was deciding what Jewish citizenship would mean.
What Barruel did with it
He did not publish it.
By his own account he withheld it because he feared it would bring violence down on Jews. He also could not reach Simonini: he tried to establish contact with the author and never managed it, then or afterwards. So the letter was not printed and not verified. It was circulated privately, among influential people in France, which is the worst of both available options — it acquired readers without acquiring scrutiny.
The last act is a strange one. On his deathbed in October 1820 Barruel told a priest that he had written a manuscript incorporating Jews into his conspiracy after all. He had burned it two days earlier.
Who wrote it
This is the genuinely unresolved question, and the retellings are more confident about it than the record supports.
A widely repeated account holds that the letter was manufactured by the French political police under Joseph Fouché, to turn Napoleon against the Jews at the moment the assembly of notables was sitting. It is a tidy explanation, it fits the timing, and it is the version most often reproduced.
It is also not established. The standard reference account of the letter does not make that finding, and scholars who have gone back to the question have argued that the claim of a police forgery is unfounded. There has been work attempting to reconstruct the life of a real Giovanni Battista Simonini, on the basis that the signature belonged to an actual Italian antisemite rather than to a desk at the ministry.
So the honest statement of the position is this. The letter exists. Its contents are false. Whether its author was a police officer inventing a Florentine informant, or a Florentine informant inventing a conspiracy, has not been settled — and the two possibilities carry very different implications. One makes the letter a state operation against a religious minority. The other makes it the work of one man who found the right reader.
What came of it
The letter's descendants are easier to trace than its parents.
The claim it advanced — a Jewish directorate behind the secret societies, aiming at control of Europe — did not die with Barruel's manuscript. It was restated, elaborated and eventually forged into documentary form as the Protocols of the Elders of Zion, which began appearing in Russia in 1903 and which was exposed as a fabrication assembled from earlier fiction. Norman Cohn's Warrant for Genocide is the standard account of that descent, and the Simonini letter sits near the head of it.
The connection should be stated with the right amount of weight. The letter is described as having inspired parts of the Protocols, and that is a judgement about intellectual ancestry rather than a documented chain of custody. Nobody has produced the copy that passed from one hand to the next.
What can be said plainly is that the structure was available in 1806, in writing, addressed to the most prominent conspiracy author of the age, and that he passed it around rather than testing it. A forgery nobody could verify, circulated privately among people disposed to believe it, is a familiar enough object. It is worth noticing that this one is more than two hundred years old.