In the article the authors put and discuss the problem of rationality in the culture of Old Russia in the context of contemporary discussions on the prob- lems of rationality. Enlighteners of Peter's time adhered to the view of the total absence of intellectual life in Old Russia. Authors distinguish various areas of intellectual activity: the study of nature, mathematical and chronological works, the use of logical tools in apologetics and polemics, medical practices, political strategies, translation activity, understanding of the (...) inner nature of man. The evolution of Old Russian language passed along the line of transformations of concrete-figurative thinking into conceptual, abstract thinking. In the processes of mastering philosophical concepts, the formation of an analytical system of language on a logico-verbal basis takes place. In the formation of a verbal-ordered language, the key role was played by symbols-concrete things, verbal and abstract. Fundamental philosophical concepts stem from symbols. Specific-proprietary and conceptual languages have different expressive and cognitive capabilities. Allegory, analogy, thought experiment, isolation of an abstract trait, visualization are typical techniques of figurative thinking. Modern Russian language absorbed the features of both figurative and logical construction. The digital era opens up new possibilities for visual methods of encoding information. (shrink)