Every year on 24 May Bulgarians celebrate the Day of the Slavonic Alphabet, one of the most revered national holidays in the country. It is an alphabet with a long and proud history that together with Greek and Latin make up the EU's only official alphabets. So what makes it so special?

People often confuse it with the Greek alphabet. I remember back in my university days in Sofia attending a lecture of a visiting professor from Western Europe. He gave a confident presentation on international finance issues and at the end left a brochure on the topic in English with some text at the back "in the Cyrillic alphabet" as he said. I was amused to find out that the text he referred to was actually in Greek and could not be of much use to Bulgarian students.

It is true that the Greek and Cyrillic scripts share some characters and this is due to how the latter one developed. In the 9th century two brothers from Thessaloniki, Cyril and Methodius, developed a system of characters that would fit the languages of the Slavonic people in Central and Southern Europe much better than either the Latin or Greek alphabets. The aim of Cyril and Methodius, who were monks, was to spread the teachings of Christianity among the recently converted Slavonic states to the north of the Eastern Roman Empire and their mission received the backing of Constantinople.

There were opponents of their work too, arguing that the word of the Bible should be taught only in the three traditional languages: Hebrew, Greek and Latin. According to texts from that pre-schism time, Cyril brilliantly defended the right of people to use their own language in their religious lives in front of the pope. "Does not the Lord send rain to all alike? Does not the sun too shine for all? And do we all not equally breathe the air? And how is it that you are not ashamed to recognise only three languages, and to command all the other peoples and tribes to be deaf and dumb?" I find this a good example of the "United in Diversity" principle that the EU proclaims nowadays. It is probably no coincidence that Cyril and Methodius are recognised as patrons of Europe.

The story has another twist. It is not actually the script of Cyril and Methodius that we Bulgarians use today. Their glagolitic script was simplified after their death by some of their disciples (notably Kliment of Ohrid). The new one adopted many Greek letters but used a number of special characters as well that would help to capture the sounds specific to Slavonic languages. The work of these disciples was carried out and found support in the thriving Bulgarian state of the time. Later the Slavonic alphabet spread also to Russia, Serbia and others where it evolved to a certain extent over the centuries. So to make this clear, no, we Bulgarians do not use the Russian letters – in fact, to an extent, it is the other way around.

Nowadays the Cyrillic alphabet is very much alive in Bulgaria and other countries but the ubiquity of the Latin script does cause some challenges. When computers and mobile phones arrived, they would not support Cyrillic letters at first so many got used to writing in Bulgarian with Latin letters. Over time solutions to these minor nuisances were found – some may still continue to write in Latin letters but this is a practice usually frowned upon. While many would recognise that there are advantages of using the Latin alphabet, Bulgarian public opinion stands firmly in favour of the Slavonic alphabet – it is just an essential part of our history and cultural identity. And many visitors to the European Parliament coming from Bulgaria are proud to see their language on top of the list of EU languages.