The purpose of this work is to identify the patterns of mythology, its system, language, and material in modern poetry - in the examples of the most prominent English author William Butler Yeats. His work as a subject of such consideration is especially indicative. Even against the background of special attention to the mythology that existed at the turn of the century, Yeats stands out as one of the brightest myth-makers, and his poetry can be considered a transitional phenomenon between romanticism and modernism. Particular attention is paid to the author's rediscovery of ancient Irish myths and legends in a new era, reviving ancient traditions in modern times.