While the nature of musical composition most often involves a state of artistic solitude and independence, the untimely death of a composer has at times made necessary the unexpected aid of a collaborator. Indeed, the list of compositions that were completed by others after the death of the composer is surprisingly varied. The most famous examples are those of Mozart's Requiem and Mahler's Tenth Symphony, but other composers -- including Puccini, Berg, and Elgar -- also left behind unfinished works that were later brought to a more complete state with varying degrees of success. Béla Bartók was surely aware of his own impending demise as he worked feverishly in order to complete his last two major works, the Piano Concerto No. 3 and the Viola Concerto, in 1945. Although the Third Piano Concerto was fully realized except for the orchestration of the final 17 bars, the Viola Concerto presented a somewhat more complex problem. Bartók's friend and pupil, Tibor Serly, was entrusted with the completion of this work, which he discussed in a 1969 interview with David Dalton:
"Bartók never worked in a reduced score or a piano reduction. He did not like to make piano reductions; he always refused to do that. Bartók was one of those rare composers who thought orchestrally. He tried to put down the orchestration as best he could so that it would be visible and possibly playable. He did not think in terms of just writing down the harmonic content, then the melody, and then going on from there. This manuscript is not a reduced sketch in any sense of the term. Where it was completed, every single instrumental part, every single particle has been put in. However, he did not mark the instruments; he made very few designations. If you could once decipher those parts, the orchestration was complete as it is. I had to clearly decipher the sketches so that everything went into place: skipped bars, additions, and other alterations. Now there are a few little places, for instance in the slow movement, where he knew exactly what he wanted to do, but put in only touches of orchestration. There are other parts, as in the last movement, where only the melodic line comes up, but he knew what was going on there; he had just not put it in."
The work, which had been commissioned by violist William Primrose in 1945, was finally premiered in 1950 by Primrose with Antal Dorati and the Minneapolis Symphony Orchestra. The concerto is divided into three movements, each linked to the next by seamless transitions of mood. The first, Moderato, begins with the first theme lightly accompanied by pizzicato cellos and basses, followed by a cadenza-like passage that leads to the entrance of the full orchestra. The movement contains three main themes, which are treated in a manner not unlike that of a Classical sonata-allegro movement. The second movement, Adagio religioso, begins with a suggestion of the work's first theme and unfolds into a more lyrical statement incorporating a rather brief moment of agitation in its center. In the final movement, Allegro vivace, Bartók makes characteristic use of dance rhythms, evoking the folk-like atmosphere and simplicity that were particular hallmarks of his earlier style.