The monograph is a contribution to the study of narratives, created in different periods of the Middle Ages and the Early Modernity, and considered as sources of the Cyrillo-Methodian tradition. The author interprets them as phenomena of identity - confessional, political, ethnic, cultural. The basic motifs presented are the national identity, the relicts of St Clemens Romanus, and the sacral languages issue, which are used as key concepts in the classification of materials. The phenomenon of turning the worship of St Cyril and Methodius into an instrument of the “national” doctrines of the Slavic peoples, manifested in different epochs and in different degrees, is studied. Important testimonies of the liturgical glorification of St Cyril and Methodius in monuments of the Latin and Greek Cyrillo-Methodian tradition are presented. Sl. Barlieva points