Mozart studied counterpoint with Martini, and composed an introduction to a symphony of Michael Haydn’s. He belonged to the same Masonic lodge as his friend Joseph Haydn (as did Stadler, a close friend, and Schikaneder), and dedicated some pieces to him. Hummel lived with Mozart as a pupil; Kelly became a close friend. Da Ponte wrote the libretti to three of his most renowned operas; Süssmayr, Mozart’s assistant and copyist, completed his Requiem after his death. Mozart engaged Salieri to teach his son (there is no clear evidence of ill feeling to Salieri, or that Mozart and the young Beethoven actually met).