Originally entitled L'Inquiétude ("Uneasiness"), this piece is part of the cycle Eloge de l'outil ("Praise of the Tool"). Here, the bass clarinet appears as a very complete instrument, with a wide ambitus, changing sonorities - Denis Levaillant uses various non-traditional techniques such as the growl, flutter-tonguing, harmonic sweep, micro-intervals - and driving velocity. The playing techniques, which are often conventional as well, constitute only one of the means used for sustaining the musical narration, for the composer has conceived a formal journey in several dimensions. The most audible of these concerns registers: the work begins in the extreme low end (with a few spikes in the upper register) and comes to an end in the highest range. Different sections are linked to one another by subtle points in common (e.g., the first sounds played: C, B flat, D, E flat, C sharp, B) evoking certain forms of variation or metamorphosis. Moreover, a dialectic creeps in between several sound and musical qualities: rhythmic or non-rhythmic passages, sound that is either normal or transformed by effects, melodic lines that are conjunct or in large intervals, etc. Here, as in other works of his, Denis Levaillant attaches great importance to the expression markings ("hesitant", "jubilant", "swept away", "swing", "mysterious", "bewitching").