What could have pushed Mozart, a few months after the completion of the original Serenade, written for sextet, to add two oboes and thus transform it into an octet? Perhaps an "external" reason. After the creation by Joseph II, in April 1782, of an "imperial harmony", there was certainly an important need for chamber music for octet. The ensemble consisting of two oboes, two clarinets, two horns and two bassoons had to perform for the most diverse occasions. As we learn from a letter from Mozart, he composes in a jiffy, as if by magic, a "Nacht Music". It is easy to see that this was the present arrangement.