Given the many facets of his work, perhaps it is not too much to say that Bartok's tormented work represents the keystone of the entire twentieth century.

Bartok's first piano works of some importance are strongly influenced by Lisztian writing (for example the Rhapsody op.1) and language, but already the 14 Bagatellas (1908) have a more dry writing. These are songs, greeted with enthusiasm by Busoni, which present a very heterogeneous language, both for technical complexity (the former, for simplicity, would even seem to be designed as songs for beginners, while no 10 and no 14 are decidedly more difficult ), both as a language. The Ten Easy Pieces were composed in the same year and somehow deepen the theme of "beginner songs" already present in the Bagatelle. The piece opens with a mysterious musical dedication, supernumerary compared to the ten pieces, in which we hear, clear and clear, again the theme-motto Stefi Geyer. The first pieces are extremely simple, yet they always have a color, an expression, a language of such interest as to make them absolutely effective even as concert pieces. As in the Bagatelle op. 14, a characteristic sign is the variety of language. There are passages with a clear popular flavour (nos 1, 2, 3, the splendid 5 that Bartok recorded several times, the 6 and 8). Others have a more experimental language. Shortly afterwards the 4 Diriges op. 9 (1910), unfortunately and incomprehensibly of rare execution. The influence of C. Debussy is immediately felt in the first one, whose music had thrilled the Hungarian composer at that time.