The most striking and significant phenomenon of French painting in the last third of the 19th century was impressionism. The innovation and ideas of this movement completely changed the artistic perception of art of the 19th and 20th centuries. The history of the study of impressionism goes back more than one century. The book “Archives of Impressionism”, published in 1939 by the famous Italian art critic Lionello Venturi, is a collection of the most valuable documents - letters from impressionist artists addressed to Paul Durand-Ruel - their constant marchand and patron, whose biography is also included in the book. The most numerous letters are from the main representatives of the group - Claude Monet, Auguste Renoir and Camille Pissarro.