Abstract: Old Russian literature is usually considered evolutionarily, in terms of the main stages of its history. However, in the 12^th century, attempts were made to present medieval bookishness as a “system of the whole.” The book offered to the reader’s attention is not devoted to evolution, but to the unchangeable essence of the Eastern Slavic art of the word. What ensured the continuity, stability of tradition, the unity of intellectual culture and specific thinking skills over the centuries? The author gives his answer to this question by reconstructing the literary custom of Old Russia. This custom was followed, but no one wrote about it. Russian medieval literature did not develop a system of rigid rules, did not know theoretical rhetoric and normative poetics. Scribes of the 11^th–17^th centuries turned to literary custom only insofar as they mastered the special methods of work and followed exemplary texts, being at the same time expressing original semantic intentions. The author of a survey and analytical study invites readers to touch the secrets of the craftsmanship and literary techniques of the Middle Ages. The book is designed for students, graduate students and teachers of humanitarian faculties and universities, appeals to philologists, historians, culturologists and a wide audience.