In the fall of 1787, a copy of the proposed United States Constitution crossed the Atlantic to reach an unusual recipient: a Neapolitan jurist who had long looked to the young American republic as a model for political and social renewal. The man who sent it was Benjamin Franklin, one of the leading figures of the American Revolution and the founding of the new republic.

The recipient was Gaetano Filangieri, author of La scienza della legislazione (The Science of Legislation), a work that had captured the American Statesman's attention and sparked an exchange of letters between two intellectuals separated by thousands of miles but united by their interest in liberty, rights and the organization of government.

The volume did not arrive until July 1, 1788, by which time Filangieri was already gravely ill. Twenty days later, on July 21, the Neapolitan philosopher died at the age of just 35. His wife, Charlotte Frendel, informed Franklin of his death in a letter dated September 27, 1788. The correspondence thus came to an end, leaving behind a little-known story that offers a glimpse into one of the most intriguing intellectual connections between the Italian Enlightenment and the birth of the United States.

Born in Cercola, near Naples, on August 18, 1752, Gaetano Filangieri came from one of the most prominent aristocratic families in the Kingdom of Naples. The third son of Prince Cesare di Arianello, he was initially steered toward a military career and life at court. He soon chose a different path, however, devoting himself to the study of law and philosophy. His intellectual development took place in the vibrant cultural circles of eighteenth-century Naples, shaped by the ideas of Antonio Genovesi and the broader currents of the European Enlightenment.

His most important work, La scienza della legislazione, began appearing in Naples in 1780. Filangieri set out to develop a comprehensive framework for reforming institutions and making the law an instrument of civic progress. Across its volumes, he addressed issues ranging from the organization of the state and criminal law to the administration of justice, public education and the economy. At the heart of his thinking was the belief that legislation should serve the public good and promote collective happiness, overcoming the privileges and inequalities that stood in the way of social development.

The work's success soon extended beyond the borders of the Kingdom of Naples. Its volumes began circulating among European intellectual circles, attracting the attention of scholars and political figures. Among them was Benjamin Franklin, who in 1781 was in Paris as the United States' minister plenipotentiary to the court of Louis XVI, negotiating an end to the war with Great Britain. Having served on the committee that drafted the Declaration of Independence in 1776, Franklin was also deeply involved in securing international recognition for the new nation.

It was in the French capital that Franklin came into contact with Luigi Pio, a Neapolitan diplomat whom he had met through the Masonic lodge Les Neuf Sœurs, which counted prominent Enlightenment figures among its members. Pio introduced him to the first two volumes of La scienza della legislazione, published the previous year in Naples. Although Franklin read Italian only with some difficulty, he was impressed by Filangieri's arguments, which he found remarkably clear and precise. He gave Pio one of his own political writings to pass along to the Neapolitan philosopher.

Their first direct contact came on August 24, 1782, when Filangieri wrote to Franklin to thank him for the gift and send him copies of his work. In the letter, he explained that he was nearing completion of the third book, devoted to criminal law, and that he still had doubts about the originality of some of his proposals on criminal procedure and the administration of justice. Having received no reply, he decided to write again on December 2 of that year. It was in this second letter that the correspondence took on a significance beyond a purely academic exchange.

Filangieri revealed that he had long wanted to leave Naples and move to the American states. The system of feudal privilege, his financial circumstances and the constraints of court life had increasingly distanced him from the environment in which he had grown up. The United States, by contrast, appeared to offer an alternative. In his letter, he described America as "the refuge of virtue, the land of heroes, the city of brothers." His ambition was not simply to emigrate, but to put his legal expertise at the service of the new republic by helping develop a comprehensive legal code that could shape its future.

Franklin replied on January 11, 1783, from his residence in Passy, near Paris. He praised the first two volumes of La scienza della legislazione and expressed interest in receiving the next installments, particularly those dealing with criminal law, an area in which he believed far-reaching reforms were needed. As for Filangieri's plans to move to America, Franklin explained that he had neither the authority to promise him a position in the new government nor the means to arrange his passage. He also urged him to visit the country first, before deciding whether to move there with his future wife, warning that people often knew the difficulties of the place they wanted to leave but could not anticipate those awaiting them elsewhere.

Filangieri's plans to reach America never materialized, but the intellectual relationship continued. In 1783, Franklin sent him a copy of Constitutions des Treize États-Unis de l'Amérique, a French-language collection of the constitutions adopted by the thirteen American States. The volume offered the Neapolitan jurist an overview of the different institutional models embraced by the former colonies after their break with Great Britain. Filangieri, for his part, continued sending Franklin new volumes of his work as they were published.

The exchange took on even greater significance in 1787, when the Philadelphia Convention drafted the proposed federal Constitution of the United States. On October 14 of that year, Franklin wrote to Filangieri once again, sending him a copy of the document recently approved by the Convention but still awaiting ratification by the States. In his letter, Franklin explained that he thought the text might interest his correspondent, given his work on legislation. He also asked him to send additional volumes of La scienza della legislazione, some of which had never reached him.

The gesture was a meaningful expression of Franklin's esteem for the Neapolitan thinker. He wanted to share with Filangieri one of the most consequential developments in American institutional history, bringing him, at least intellectually, into a discussion about the new federal system. Their exchange touched on questions that would become central to modern constitutionalism: the rule of law, the protection of rights, freedom of trade and industry, and the need to build institutions oriented toward the common good.

The significance of this relationship, however, must be understood carefully. There is insufficient evidence to claim that Filangieri wrote or directly shaped the text of the U.S. Constitution. The document emerged from a complex political process involving the delegates to the Philadelphia Convention, whose discussions drew on a range of legal and philosophical traditions. What is documented is Franklin's interest in the Neapolitan's work and the exchange of ideas between the two men on the principles that should guide legislation and the institutions of the new republic.

A detail preserved in the archives offers a tangible glimpse of this relationship. In a copy of La scienza della legislazione held at the library of the American Philosophical Society in Philadelphia, Franklin placed a mark beside a passage in which Filangieri described peace as the first law of nations and war as one of humanity's greatest evils. The annotation is evidence of Franklin's attention to the Neapolitan jurist's ideas and reflects a broader convergence of views on the need to promote stability, cooperation and progress through institutions.

Geographical distance and the slow pace of communication prevented the two men from ever meeting in person. Their relationship remained confined to letters, books and documents crossing the Atlantic. The federal Constitution Franklin had sent in October 1787 reached Filangieri on July 1, 1788, when the jurist's health was already failing. He died on July 21, leaving La scienza della legislazione unfinished. Its fifth book was published posthumously in 1791.

The final account of their exchange came from Filangieri's wife, Charlotte Frendel, who wrote to Franklin in French on September 27, 1788, to inform him of her husband's death. She explained that the American Statesman's letter and the copy of the Constitution had arrived on the very first day of Filangieri's illness. Had he been able to do so, she added, her husband would have replied personally and sent Franklin the volumes of his work he had requested. She promised to take care of this herself.

The correspondence has been examined in depth by Professor Amedeo Arena, a professor of European Union law at the University of Naples Federico II. His archival research identified and analyzed nine letters and their accompanying materials: six written by Filangieri to Franklin, two by the American Statesman to the Neapolitan jurist, and one by Filangieri's widow. The documents are held at the American Philosophical Society and the Historical Society of Pennsylvania in Philadelphia, as well as the Museo Civico Filangieri in Naples. Arena's research also helped distinguish the authentic correspondence from two other letters that had been mistakenly attributed to the exchange between the two men.

The story of Filangieri and Franklin offers a less familiar perspective on the founding of the United States. At a time when Italy was not yet a unified country, Naples was one of the most vibrant centers of the European Enlightenment, and its intellectuals were part of a network of relationships that stretched across the continent and reached America. The Neapolitan jurist never fulfilled his dream of moving across the Atlantic, but his ideas nonetheless entered into dialogue with those of one of the leading figures of the American Revolution.

Two hundred and fifty years after the Declaration of Independence, an anniversary celebrated across the United States on July 4, 2026, the correspondence offers an opportunity to rediscover the contribution of the Italian Enlightenment to the circulation of ideas surrounding the birth of the American republic. It is a story that begins in Naples and reaches Philadelphia, showing how debates over rights, liberty and the future of government had already transcended national borders by the late eighteenth century.