Wolfgang Amadeus Mozart wrote his Symphony No. 40 in G minor, in 1788.
It is sometimes referred to as the “Great G minor symphony,” to distinguish it from the “Little G minor symphony,” No. 25. The two are the only extant minor key symphonies Mozart wrote.
The 40th Symphony was completed on July 25, 1788. The composition occupied an exceptionally productive period of just a few weeks in 1788, during which time he also completed the 39th and 41st symphonies (June 26, and August 10, respectively).