The Grand Duchy of Lithuania adopted the administrative practices and the legal system of Rus and a state language that was Old Slavonic, heavily imbued with vernacular Ukrainian and Belorussian.
In the ninth century saints Cyril and Methodius devised a written form of the Slav language and the new churches came to use translations of the Orthodox liturgy into the Old Slavonic language made by their disciples.
In 1777 Maria Theresa secured the erection of a diocese for the Uniat Greeks, with the Eastern Rite and the Old Slavonic Liturgy.
That is what is missing when he explores the archaeology of Old Slavonic in the Glagolitic Mass, and it is what is triumphantly present in the song cycle The Diary Of One Who Disappeared, directly inspired by his love for Stosslova.
It retains over 2,000 words from the pre-Cyrillic Old Slavonic tongue.