On today’s date in 1943, the Boston Symphony and conductor Serge Koussevitzky gave the first performance of a “Symphony for Strings” by the American composer William Schuman.

Schuman was just 33 years old at the time, but Koussevitzky had already been programming and commissioning Schuman’s music for about 5 years. Koussevitzky had already given the premiere performances of his popular “American Festival Overture” and the Third Symphony.

Schuman’s “Symphony for Strings” is dedicated to the memory of Koussevitzky’s wife, Natalie, whose family fortune that enabled Serge Koussevitzky to establish himself as a conductor, found a publishing house, and commission many of the 20th century’s most significant works, including Stravinsky’s “Symphony of Psalms” and Bartok’s “Concerto for Orchestra.”

In Russia, the Koussevitzkys championed Russian music. In France, they supported French composers. And, beginning in 1924, when Koussevitzky became the music director of the Boston Symphony, many American composers benefited from this remarkable couple’s enthusiasm for new music. Schuman’s “Symphony for Strings” is just one of a long list of the Koussevitzkys’ American commissions, which includes works by Aaron Copland, Roy Harris, Samuel Barber, Walter Piston, and Leonard Bernstein.

Taken as a whole, the concert music commissioned by Serge and Natalie Koussevitzky remains one of the most remarkable musical legacies of the 20th century.