This book analyzes the unique character of Medieval Russian literature and the principles of fable building in professional and folk texts. The author studies some specifics of the texts dating back to Moscow Rus (16th - 17th century) and the earlier Kievan period. The two main topics 1) a problem of interpretation of "The Song of Igor's Campaign" (12th century) and of other historically and artistically related texts; and 2) the evolution of a narrative genre as a result of the interaction between written Christian and oral folk cultures. Bibliographic references.