This article is devoted to the analysis of correspondence between Kandinsky and Schoenberg. The article quotes from the personal letters of two major artists of the XX century - Kandinsky, one of the initiators of abstract painting, and Schoenberg, the founder of atonal sound in music. The author considered the key theoretical works and works of art, as well as the opinions of experts and researchers. The study focuses on the similarities and differences in the approaches of the two authors. Particular attention is paid to the problem of interaction between image and sound, which is considered on the example of works by Kandinsky and Schoenberg. The article deals with one of the important problems of the XX century - the problem of creating a single or synthetic work of art.