These are not organically conceived and designed works, because Siri was primarily a diarist and a collector of materials, but taken together they constitute a vast treatment of European history spanning more than half a century.

The use of archival materials (which King Cardinal Richelieu minister was the first to allow him) offered him solid information, and on that basis he manifested a vigilant historical sense trained in understanding political facts.

But in 1640, while in Venice, he began - under the pseudonym Captain Latino Verità - a heated polemic advocating the establishment of a league between the Serenissima, the Pope and France in favor of the “freedom of Italy” oppressed by Spain.

[2] In 1640, Siri published a book about the occupation of Casale Monferrato (Il politico soldato Monferrino) defending the French position.

[3] Besides the Mercurio Politico Siri wrote another historical work, entitled Memorie Recondite, which fills eight volumes.

[5] Cardinal Mazarin honored Siri with a pension and the title of Counsellor of State, chaplain and historian of the king of France.