Picture the Italian peninsula in the early 14th century. It’s not the unified nation we know today, but a patchwork of city-states, kingdoms, and papal territories. Just as there is no single “Italy”, there is no single “Italian language.” If you were a scholar, a priest, or a lawyer, you wrote and communicated in Latin—the universal language of power, religion, and academia. But if you were a merchant, a farmer, or an artisan, you spoke your local dialect, your volgare, a language that could change dramatically just a few dozen miles down the road.

Into this fragmented linguistic world stepped a poet from Florence, a man in political exile with a vision that would change his homeland forever. That man was Dante Alighieri. While he is celebrated worldwide for his epic journey through the afterlife in The Divine Comedy, his most profound and lasting legacy is arguably the language he used to write it. Dante is not just a titan of literature; he is revered as il Sommo Poeta (the Supreme Poet) and, more importantly, il Padre della Lingua Italiana (the Father of the Italian Language).

A World of Two Languages: Latin vs. the Vernacular

To understand the scale of Dante’s achievement, we have to grasp the linguistic hierarchy of his time. Latin was the king. It was stable, sophisticated, and universal (across the educated Christian world). It was the language of God, of Roman law, and of Virgil—the very poet Dante so admired. The various local vernaculars, on the other hand, were seen as the “vulgar” tongues, not in the sense of being crude, but in the original Latin meaning of vulgaris: “of the common people.”

These vernaculars were living, breathing, and constantly changing. A Sicilian speaker would struggle to understand a Venetian. A Roman’s speech would sound foreign to a Lombard. These languages were considered suitable for daily chatter, marketplace haggling, and folk songs, but not for serious, high-minded literature or philosophy. To write about theology or the cosmos in a local dialect would have been like trying to build a cathedral out of mud bricks. It just wasn’t done.

The Theory: Dante’s Defense of the People’s Speech

Dante had a different, radical idea. Before he even completed his Comedy, he laid out his linguistic theory in a treatise titled De Vulgari Eloquentia (“On Eloquence in the Vernacular”). In a move dripping with irony, he wrote this passionate defense of the vernacular… in Latin. He had to, as it was the only way the audience he needed to convince—the educated elite—would take him seriously.

In this work, Dante argued that a vernacular could be just as noble, expressive, and beautiful as Latin. He systematically analyzed over a dozen dialects from across the peninsula, searching for an “illustrious vernacular” (volgare illustre) that could serve as a unifying literary language for all Italians. He criticized the guttural sounds of some, the soft-spoken nature of others, and found fault in almost all of them, including his own native Tuscan. What he was looking for was an idealized language, a refined version that could be curated from the best elements of all dialects.

While he never quite found this perfect, pre-existing language, he set the stage for its creation. He had built the intellectual framework. Now, he needed to provide the ultimate proof.

The Proof: The Divine Comedy

If De Vulgari Eloquentia was the manifesto, The Divine Comedy was the revolution. Dante made the audacious choice to write his grand epic—a poem about the state of souls after death, the nature of sin, and the path to divine love—not in Latin, but in his own Florentine dialect of the 14th century.

This was a gamble of epic proportions. He used the language of the Florentine streets to describe the very architecture of the universe. And in doing so, he demonstrated its incredible power and flexibility. The language of his Comedy is a testament to the vernacular’s expressive range:

• In the Inferno, his language is harsh, gritty, and visceral. He uses clipped consonants and guttural sounds to describe the torments of the damned. Consider the demonic guardian Plutus’s nonsensical cry:
  

  “Pape Satàn, pape Satàn aleppe!”

  The words are jarring and ugly, perfectly capturing the alien and terrifying nature of Hell.

• In the Paradiso, the language transforms. It becomes sublime, ethereal, and filled with light. He coined new words, called neologisms, to describe concepts that had never been expressed in the vernacular before, such as trasumanar (“to transcend the human”) or inurbarsi (“to become urban”, used to describe how a soul enters a heavenly body).

Dante’s masterpiece was a sensation. Because it was written in a vernacular, it was accessible to a far wider audience than a Latin text would have been. Merchants, nobles, and even some literate commoners could read it or listen to it being read aloud. Copies of the manuscript spread rapidly across Italy. Readers from Venice to Sicily were captivated, and in the process, they absorbed the Florentine dialect. Dante’s language became the gold standard.

The Legacy: Cementing a National Language

Dante didn’t work in a vacuum. Two other great Tuscan writers of the 14th century, Petrarch (Francesco Petrarca) and Boccaccio (Giovanni Boccaccio), followed his lead, writing their own masterpieces in the Florentine vernacular. Together, Dante, Petrarch, and Boccaccio became known as the Tre Corone (“Three Crowns”) of Italian literature. Their collective success cemented the prestige of the Tuscan dialect above all others.

For centuries after, Italian intellectuals debated the Questione della Lingua (“The Question of the Language”): which dialect should be the official one? The answer, time and again, pointed back to the model created by Dante and the other Tuscan masters.

The final seal of approval came in the 19th century, just as Italy was becoming a unified country. The Milanese writer Alessandro Manzoni, wanting his influential novel I Promessi Sposi (The Betrothed) to be a linguistic model for the new nation, famously traveled to Florence to “rinse his cloths in the Arno”, revising his entire text to conform to the modern Florentine dialect—the direct descendant of Dante’s language.

So, while Dante didn’t “invent” Italian, he did something far more important. He took one dialect among many, polished it, enriched it, and used it to create a work of such genius that it became the undeniable standard. He gave a fragmented people a common literary voice, laying the foundation for the language that would one day unite a nation. Every time you hear the melodic sounds of modern Italian, you are hearing the echo of a 14th-century poet who dared to believe that the language of the people was worthy of the divine.