Completed on August 21, 1949, in Carpinteria, California. Dedicated to the brilliant Monique Haas, a student of Lazare Lévy, it received its broadcast premiere on March 4, 1950, performed by Haas on BBC Radio in the UK. It consists of four movements: fast, fast, slow, fast. For the interpretation of this ambitious work from his mature period, an understanding of Milhaud's unique perspective on sonata form is essential. It goes without saying that Milhaud, appointed professor of composition at the Paris Conservatoire as the successor to the academic luminary Henri Büsser, was thoroughly familiar with all aspects of traditional sonata form. However, in his practical composition, he was most wary of form restricting free creativity. He himself stated that he disliked leaving traces of laborious development of themes or motives, and preferred a method of generously deploying abundant melodies to give an impression divorced from ossified stylistic conventions. According to his student, Sadao Bekku, Milhaud would sometimes, during composition classes, cite Mozart's piano sonatas as examples to concretely demonstrate to his students how unrestrained freedom and formal beauty could coexist without contradiction. It is important to confirm that all of Milhaud's compositions—symphonies, concertos, and instrumental sonatas—are practical applications and extensions of this fundamental stance.

Paul Collaer praised the overflowing melodic richness of this work. Jean Roy saw happiness, grace, and freedom expressed through its relaxed writing. Indeed, it can be said to be a masterpiece, fully demonstrating Milhaud's mature and skilled writing from his middle period, and possessing rich content. More than 30 years after his Piano Sonata No. 1 (Op. 33), there are many notable changes in his compositional style, including his use of polytonality. The large-scale, clashing polytonality frequently found in the First Sonata has receded; here, the contrapuntal treatment of fluent melodic lines forms the core of his writing, with polytonality primarily emerging incidentally from the intertwining of melodies. Even the same melody can change tonality depending on the context in which it appears. The highly refined writing conveys the weight of the years separating the two sonatas. It is regrettable that this work has significantly fewer performance opportunities compared to its importance. Not only does the high technical standard demanded by this work deter performers, but there is also a tendency for dissatisfaction to be directed at the perceived difficulty in grasping its structure. However, as Jean Roy testified, even during Milhaud's lifetime, there were objections from both sides: conservatives in the music world criticized the perceived weakness of Milhaud's compositional structure, while radicals insisted that Milhaud clung to traditional forms. Milhaud was an independent spirit who kept his distance from all schools of thought. Contemporary performers and listeners should not align themselves with any of these biased opinions, which were rooted in the factional conflicts of the music world of that era. We should, above all, respect the sonata compositional method clearly articulated by the composer himself. We hope for an active engagement with this work through an objective evaluation and calm interpretation.

Movements

• First Movement: Alerte (Lively). 4/4 time, primarily G-sharp minor (no key signature). Includes the Phrygian mode.
• Second Movement: Léger (Lightly). 7/8 time, begins in B-flat major and ends in G major (no key signature).
• Third Movement: Doucement (Gently). 3/4 time, primarily A major (no key signature).
• Fourth Movement: Rapide (Fast). 2/2 time. Begins in C major and ends in E major (no key signature).