Throughout his career, Alfredo Casella (1883-1947) seemed to make a particular case of French master Claude Debussy. During his training period in France (1896-1915), Debussy was a major source of inspiration to the young composer seeking his own personal style. Back in Italy, Casella encouraged young composers to inspire themselves of European techniques, including those of Debussy, to modernize the Italian instrumental music. However, with the promotion of the Italian musical past, aiming the creation of a national art, Casella gradually adopted a different position, event diametrically opposed, regarding Debussy’s music. Then the French composer is not considered as a model anymore, nor even, a “dream for the future generations,” but rather, according to Casella, the author of a language entirely incompatible with “the profoundly Italian spirit.” We propose a critical, historical and aesthetical study of Casella’s works from 1902 to 1930. We shall try establishing a methodological link between the assertions and opinions in Casella’s writings and their application in his musical works, by the means of the argumentation developed by the musician.