The musical improvisations presented in “C'est pour quoi” underline the convergences and divergences between the intentions of the individual and their repercussions on the collective (and vice versa). Diffused by a spatialized device associating intimate listening and collective listening, the music results from the interaction between computer agents embedding "musical memories" and the "stimuli" provided by improviser musicians. “C'est pour quoi” presents improvisations in duo between a "human saxophone musician" and a "human machine musician" using machine learning technologies for real-time interactive creation, in a form that is frozen by the recording. Freeing itself from the usual didacticism in the field of "creative AI" – that focuses all its attention on the tools – the installation fosters the confusion of sources and roles. It presents the "naked" finality of creative processes using instruments of a new generation to exploit the creative practices they offer: meta- improvise and compose at the level of intentions and narration. Musicians partners of the project: Rémi Fox, Steve Lehman.