Sometimes it’s all very personal: a piece of music is written for a particular orchestra or even a particular conductor.

That certainly was the case with this work, the Sixth Symphony of the Czech composer Bohuslav Martinu, a work he gave the French title, “Fantasies symphoniques.”

The work was commissioned as part of the 75th anniversary season of the Boston Symphony, an orchestra for which Martinu must have had warm feelings. The long-time conductor of the Boston Symphony, Serge Koussevitzky, had championed Martinu’s music in America, and even found Martinu a job teaching composition at the Berkshire Music Center in Massachusetts.

In the early 1940s, Martinu had fled Paris as the German troops approached. He had already fled German-occupied Czechoslovakia, where his music had been banned, and was struggling to establish himself in America. Koussevitzky and the Boston Symphony commissioned and premiered his First and Third in 1942 and 1945.

Martinu’s Sixth Symphony was dedicated to Koussevitzky’s successor in Boston, the French conductor Charles Munch. Munch was an old friend of Martinu’s from his days in Paris. Like Koussevitzky, Munch was a Martinu enthusiast, and was particularly famous for his dazzling interpretations of the French Romantic composer Hector Berlioz. Martinu’s new symphony was intended to be something like a “new” version of Berlioz’s famous Symphonie fantastique, tailor-made for the French conductor.