Fortunately, his music is catalogued thanks to Ludwig von Kochel, with each piece labelled with a K or KV numbering system. For example, Mozart's Requiem in D Minor was, according to Köchel's counting, the 626th piece Mozart composed. Thus, the piece is designated K. 626 or KV 626. Köchel catalogue numbers not only attempt to establish chronology, but also give a helpful shorthand to refer to Mozart's works.
Other years I have had parties with German food and powdered wigs! And sacher torte thrown in! It's a happy excuse to have a gathering, but honestly, I love his music, party or no. I honor this day, as do so many others. Check out some beautiful quotes about him and his music:
O Mozart, immortal Mozart, how many, how infinitely many inspiring suggestions of a finer, better life have you left in our souls! -- Franz Schubert, Diary, 1816
Mozart’s music is so beautiful as to entice angels down to earth. (Franz Alexander von Kleist)
Mozart is the highest, the culminating point that beauty has attained in the sphere of music. (Tchaikovsky)
Mozart’s music is the mysterious language of a distant spiritual kingdom, whose marvelous accents echo in our inner being and arouse a higher, intensive life. (E. T. A. Hoffmann)
So, there it is, what more can one say!