Nevertheless, the first movement of what would come to be known as Symphony No. 35 was completed within a week and sent back to his father in Salzburg; over the course of the next several weeks, the remaining movements were finished and mailed as well. Based on historical evidence, it is highly probable Mozart did not meet his fathers deadline. Nonetheless, the delay was justified as it resulted in one of the finest works of the young composers career. (It must be noted that some believe that Mozarts father purposely timed the request for the symphony because he disapproved of Mozarts plans to marry Constanze; this theory holds particular credence when one considers historians are unsure if the ennoblement of Sigmund Haffner ever occurred.)
Months later (March 1783), Mozart was involved in creating an academy of music at the Burgtheater in Vienna. Wanting to perform the symphony he had so quickly rushed to his father, he wrote to Leopold Mozart requesting the score. Many weeks later, and after several exchanges of letters, Leopold sent the symphony back to Mozart. Impressed by the work he had long forgotten, Mozart wrote to his father, Most heartfelt thanks for the music you have sent me...my new Haffner symphony has positively amazed me, for I had forgotten every single note of it. It must surely produce a good effect. Mozart was correct. The performance at the academy was a huge success.