The creators of Slavic writing, the brothers Constantine (who received the monastic name Cyril shortly before their death) and Methodius are revered throughout the Slavic world. It is no coincidence that their life feat is equated with the apostolic one, calling them the “first teachers” of the Slavs. Natives of the Greek Soluni (Thessaloniki), they not only created the alphabet, which is still used by many peoples (and not only Slavic ones!), but also translated the Gospel and liturgical books into the Slavic language, allowing the Slavs to pray to God in their native language. The biography of Saints Cyril and Methodius offered to the attention of readers belongs to the pen of the writer Yuri Mikhailovich Loschits, whom connoisseurs of the biographical genre are well aware of as the author of the books “Frying Pan”, “Goncharov” and “Dmitry Donskoy”, previously published in the series “Life of Remarkable People”. The two oldest literary and historical monuments of Old Church Slavonic writing - “The Life of Constantine the Philosopher” and “The Life of Methodius” (the so-called lengthy lives of the Thessalonica brothers) - became reliable guides for the author. Many pages of the book are written as an extended commentary on these monuments of a distant era and represent an experience in artistic and research reconstruction.