Composed in 1778, the Symphony no. 40, KV. 550, is sometimes referred to as the "Great G minor symphony," to distinguish it from Symphony no. 25, the two being the only extant minor key symphonies Wolfgang Amadeus Mozart ever wrote. Scholars have often suggested that Mozart never heard his 40th symphony performed, some going as far as suggesting that the work was written for posterity. However, a recently discovered letter supplies evidence for at least one performance of the work with Mozart present. Most important is the fact that Mozart revised his symphony to include clarinets, a trouble he would have hardly gone through had he not had a specific performance in view. The symphony calls (in its revised version) for flute, 2 oboes, 2 clarinets, 2 bassoons, 2 horns, and strings. Notably missing are trumpets and timpani. The first theme is well known, and it also appears in the first movement of his Piano concerto no. 21. Robert Schumann regarded the work as possessing "Grecian lightness and grace". Almost certainly, the most common perception today is that the symphony is tragic in tone and intensely emotional.