The book was written by a major French linguist A. Meillet and is devoted to describing the ancient state of Slavic languages. When establishing a common Slavic language, the author uses a comparative historical method, attracting the testimony of other Indo-European languages, data from Slavic writing and modern Slavic languages. The work is distinguished by the richness of the material attracted, the depth of interpretation of many linguistic phenomena, a number of interesting etymologies, as well as the harmony of presentation.