By Jennifer Paxton, Ph.D., The Catholic University of America
The study of the relationships between the Celtic languages started when England almost fully conquered Ireland, and the Gaelic culture began to decline due to the Jacobite rebellions. So, non-Celtic speakers became interested in rediscovering the Celtic phenomenon when the Celts were not a military threat anymore. The investigation of the Celtic languages continued well into the 17th and 18th centuries and brought back some elements of the Celtic identity.

Paul-Yves Pezron
The linguistic studies on the Celtic language that were conducted by George Buchanan were followed by more serious research 100 years later. A French scholar, Paul-Yves Pezron conducted those investigations that brought real progress on Celtic Linguistics. So, this scholarly research did not take place in Ireland but the Brythonic world. Living from 1639 to 1703, Pezron was a Cistercian monk from Brittany and knew the Breton language. His book Antiquité de la Nation et de la langue celtes autrement appelez Gaulois was published in 1703, and three years later, it was published in English, titled The Antiquities of Nations; more particularly of the Celtae or Gauls.
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Using an early version of comparative linguistics, he found that Breton was the last remaining branch of Gaulish. He believed that Gaulish was a branch of a language spoken at the time of the Tower of Babel. But he was mistaken because Breton was the language of British immigrants in Brittany in the 5th Century. Still, he identified the connection between Breton and Welsh, which made Welsh a Celtic language.
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Edward Lhuyd’s Contribution

After Pezron’s work was published in English, a Welshman called Edward Lhuyd continued his work. He lived from 1660 to 1709, and was the curator of the Ashmolean Museum at Oxford University. He had relations with prominent intellectual figures like Sir Isaac Newton. Lhuyd admired Pezron for his work and had extensive knowledge of early Celtic studies.
He made a significant contribution by comparing the vocabulary of Welsh, Irish, Scottish Gaelic, Cornish, and Breton and brought all the Celtic languages together. Although he did not refer to the languages of the British Isles and Ireland as Celtic, he discovered they were related. His significant discovery was the sound changes between Welsh and Irish, which indicated the distinction between q-Celtic and p-Celtic languages. He referred to q-Celtic and p-Celtic speakers as Goidelic and Brythonic, respectively, named after the characters in the Book of Invasions.
Celtic Culture Revival in Wales
At the time of the above linguistic investigations, a similar process was being undertaken in Wales. It first started in the mid-18th century when an English vicar named William Stukeley proposed that druids had worshiped in stone monuments like Stonehenge and Avebury. But it is now discredited because Stonehenge is so old that actual druids could not have built it. Before that, a German writer had pointed out that druids wore white robes, which was widely accepted and led to a spread of druid craze to Wales. The first Druidic Society was established on the Welsh island of Anglesey in 1772. It had some roots in the past as Anglesey was a center of druidism during the Roman times.
Another attempt was to revive the forgotten traditions of the Welsh bards. This tradition can be traced back to the 12th Century when a powerful Welsh ruler, Lord Rhys of Deheubarth, held a poetry competition at his Cardigan court. These competitions, called Eisteddfod, which means “session”, continued during the Middle Ages and stopped in the 17th Century. In 1789, Thomas Jones decided to bring them back.
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The Influence of Iolo Morganwg
The most influential person in the revival of the Welsh culture was Iolo Morganwg, whose real name was Edward Williams, and was interested in both poetry and druidism. To revive the poetry sessions, he founded the Gorsedd Beirdd Ynys Prydain, an organization for the bards of the island of Britain, in 1792.
To prove continuity with the ancient bards and druids, he even forged some poetry by the very famous 14th-century Welsh poet Dafydd ap Gwilym.
The Eisteddfod continues, and today it is one of the key cultural institutions of Wales. Both the poetic and druid revivals are still alive today. But druidism is divided into two religious and nonsectarian branches.
No matter if all these revivals are based on genuine traditions or completely invented, they are now parts of the modern Celtic culture.
Common Questions about Linguistic Research on Celtic Languages
Adopting an early version of comparative linguistics, Paul-Yves Pezron found that Breton was the last remaining branch of Gaulish. He also discovered the connection between Breton and Welsh, which proved Welsh was a Celtic language.
Edward Lhuyd was a Welsh scholar whose significant discovery was the sound changes between Welsh and Irish, which indicated the distinction between q-Celtic and p-Celtic languages. He referred to q-Celtic and p-Celtic speakers as Goidelic and Brythonic, respectively, named after the characters in the Book of Invasions.
Iolo Morganwg was the most influential person in the revival of the Welsh Celtic traditions. He was interested in both poetry and druidism. To revive the poetry sessions, he founded the Gorsedd Beirdd Ynys Prydain, an organization for the bards of the island of Britain in 1792.