Glagolitic is among the few scripts in history whose invention can be placed with a person, a purpose and a date. In 862 the Moravian prince Rastislav asked Byzantium for teachers who could preach in the Slavic tongue, and the emperor sent two brothers from Thessalonica, Constantine the Philosopher, remembered as Saint Cyril, and Methodius. For the mission, around 863, Constantine devised a wholly new alphabet fitted precisely to Slavic phonology, with letters for sounds no Greek script could write, and with it he and his circle translated the Gospels and the liturgy into the dialect now called Old Church Slavonic. The letterforms are original: they draw on Greek minuscule and possibly on Semitic models, and medieval tradition read symbolic intent into them, the first letter, for the word az, being formed of a cross. The script's name comes from the Slavic glagolati, to speak.
The brothers defended Slavic worship in Rome against the view that liturgy belonged only to Hebrew, Greek and Latin, and won papal approval for it, a landmark in the principle that a people may pray in its own language and letters. Tradition also credits the brothers with training the first generation of Slavic clergy to read and copy the new script, planting a scribal culture along with an alphabet.