More than 1,000 years ago in Spain’s La Rioja region, monks made notes in the margins of Latin texts. These are believed to be the Spanish language’s first steps onto the page.

After a short drive uphill from the small village of San Millán de la Cogolla, I found myself standing before the Suso monastery. Founded by the 6th-Century hermit monk St Millán, the monastery feels as if it belongs to another time and place. From this secluded spot surrounded by woodland, I had views of the Cárdenas Valley below and Mount San Lorenzo’s peak in the distance. Around me, bluebells marked the entrances to mountainside caves where monks lived long before Suso’s construction.

I was in Spain’s La Rioja region, a part of the country that draws visitors for its famous vineyards and the Camino de Santiago pilgrimage route. But I was here to learn about how the region shaped the way in which millions of people around the world communicate with one another.

I could feel the walls reverberate with the rumblings of linguistic history

As I walked through the monastery’s cool, dark corridors, I could feel the walls reverberate with the rumblings of linguistic history. Standing in silence, it was easy to picture monks hunched over Latin manuscripts, furtively making notes in the margins about the meanings of the scriptures in the local language more than 1,000 years ago.

That language is what we now call Spanish.

The official language in 20 countries and the mother tongue of 480 million people around the world, Spanish is the second most widely spoken native language on the planet after Mandarin Chinese, according to the Spanish language institute, the Instituto Cervantes. In San Millán de la Cogolla, I listened to words roll off locals’ tongues in rapid succession as they discussed the weather and exchanged news about their families – as if this complex language had always existed.

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Professor Jairo Javier García Sánchez, of the department of philology, communication and documentation at the University of Alcalá on the north-eastern outskirts of Madrid, traces the origins of Spanish back to Latin, “but not written, literary, classical Latin, rather of an evolved Latin more in agreement with that of the spoken language of late epoch and even of the archaic.” This Latin is what is known as vulgar Latin – “vulgar” referring to common, colloquial language as opposed to the derogatory sense, he explained.

Latin came to the Iberian Peninsula with the Romans during the Second Punic War in the 3rd Century BC, when the formation of Ibero-Romance, a sub-group of the Romance languages that developed on the Iberian Peninsula, began. This evolutionary process took place as the native inhabitants adopted Latin and incorporated it into their local language, phonetics, vocalic system and lexicon.

While there is “no concrete moment in which Latin dies and Spanish is born,” according to García Sánchez, what can be traced to a birthplace of sorts is the earliest form of written Castellano, or Castilian, the form of Spanish from the Iberian Peninsula.

Claudio García Turza, director of the Department of the Origins of the Spanish Language at the International Centre of Investigation of the Spanish Language (CILENGUA), has dedicated more than 40 years to the investigation and teaching of Spanish at the University of La Rioja. We met at the grandiose Yuso, Suso’s larger and more majestic sister monastery located at the bottom of the hill. Both monasteries earned Unesco World Heritage status in 1997.

García Turza explained that in the 10th Century, one of the monastery’s monks began to translate sermons and prayers – all of which were written and recited in Latin, which by then wasn’t universally understood – into the local Ibero-Romance dialect for his fellow monks to understand. He left notes in the margins of the original texts. Those translation notes, the most famous of which have been compiled in Las Glosas Emilianenses, or the Emilian Glosses, are some of the language’s earliest steps onto the page.

“[They] provide a glimpse into how the language was spoken all those centuries ago, in a time when most people were illiterate,” García Turza said as he leaned forward, his voice rising with excitement.

Suso’s role in the development of the Spanish language doesn’t end there. Several centuries later, poet Gonzalo de Berceo resided at the monastery, where he wrote verses that included never-before-seen terms. Recognised as the first Spanish-language poet, de Berceo expanded the Spanish lexicon by more than 2,000 words during his lifetime.

Between them, Suso and Yuso attract more than 100,000 visitors every year. Nine monks still call a wing of Yuso home and educate visitors on the monastery’s Baroque architecture. As I explored the tranquil complex, I caught a glimpse of immense bull skin-clad choir books, each weighing between 20-60kg, in the upper cloister. Another of the house treasures – though it is not included on the monks’ guided tour – is the library, which brims with more than 10,000 books from the 11th to 18th Centuries, including one where the region’s name, Rioja (from the name of the local river Río Oja), is documented for what’s thought to be the first time.

Also on display at Yuso is a replica of Las Glosas Emilianenses (the original translations are now preserved in the Royal Academy of History in Madrid).

Other early examples of written Ibero-Romance exist, including the Cartularios de Valpuesta, medieval documents containing words in Ibero-Romance found at the monastery of Santa María de Valpuesta in the neighbouring province of Burgos. Belén Almeida Cabrejas, García Sánchez’s colleague at University of Álcala, was keen to point out that all early texts are valuable in demonstrating Ibero-Romance on its journey of evolution. “It’s difficult to say which text is the first written in Romance,” she said, because that depends on the criteria used to define what “written Romance” is.

It is the house of words, but first and foremost, the house of philology

Yet there is no doubt that the Suso monastery played a crucial role in the development of the Spanish language. García Turza called it “the house of words, but first and foremost, the house of philology”. He explained that the longest of the monk’s notes, known as Glosa 89, constitutes the first comprehensive text written in an Ibero-Romance language, where “a succession of words… are stitched together, interrelated, to convey a message.” It’s the first full text where all linguistic levels of the language are expressed – not only with words, but also grammar and syntax – providing evidence of a greater complexity.

According to García Turza, if the Suso monks were the first to record the sounds of the Ibero-Romance language on the page, they are also responsible for the creation of the Spanish alphabet. “Here is the invention of Spanish writing, [where] the invention of the Spanish alphabet is realised,” García Turza said.

It’s understandable, then, that the renowned 20th-Century Spanish poet and philologist Dámaso Alonso called the Glosa 89 ‘el primer vagido de nuestra lengua’, or ‘the first cry of our language’.

And with the Instituto Cervantes predicting 756 million Spanish speakers by the year 2050, one thing is for sure: we’re a long way from hearing the last.

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