Abstract: The research subject is the creative work of one of the most mysterious composers of the 19th century Charles-Valentin Alkan. The authors give some facts of the composer’s biography to answer the question about his disappearance from the scene of Romantic music despite the continuing work of the great genies of Romanticism: Chopin, Liszt, Rubinstein, etc. The authors study the example of the set of “12 études dans tous les tons majeurs” Op. 39 to demonstrate the unique style of Alkan crystallized in collaboration with the composers of the previous epochs and his contemporaries. Due to the lack of the Russian studies of the issue, the authors analyze the works of foreign authors to evaluate the artistic legacy of Alkan. The authors attempt to break the Alkan semantic code using the example of the piece 12 Op. 39  Le festin d'Ésope (Aesop's Feast), which the outstanding performers have been trying to crack for more than 50 years, positioning the meaning of their interpretations. The article contains the authors’ conclusions about the urgent necessity to study the work of Alkan in within the Russian musicology.