Mozart has always been pointed to by preference to show how a really great master shakes his melodies from his sleeves, as it were. Yet, on reading Jahn's elaborate account of Mozart's life and works, nothing strikes one more than the emphasis he places on the amount of preliminary labor which Mozart expended on his compositions, before he wrote them down. It appears to be a well-authenticated fact that Mozart postponed writing the overture to "Don Giovanni," until the midnight preceding the evening when the opera was to be performed in public; and that at seven o'clock in the morning, the score was ready for the copyist, although he had been drinking punch and was so sleepy that his wife had to allow him to doze for two hours, and kept him awake the rest of the time by telling him funny stories. But this incident loses much of its marvellous character, when we bear in mind that Mozart, according to his usual custom, must have had every bar of the overture worked out in his head, before he sat down to commit it to paper. This last labor was almost purely mechanical, and for this reason, whenever he was engaged in writing down his scores, he not only worked with amazing rapidity, but did not object to conversation, and even seemed to like it; and on one occasion when at work on an opera, he wrote as fast as his hands could travel, although in one adjoining room there was a singing teacher, in another a violinist, and opposite an oboeist, all in full blast! Mozart himself tried to correct the notion, prevalent even in his day, that he composed without effort--that melodies flowed from his mind as water from a fountain. During one of the rehearsals of "Don Giovanni," at Prague, he remarked to the leader of the orchestra: "I have spared neither pains nor labor in order to produce something excellent for Prague. People are indeed mistaken in imagining that art has been an easy matter to me. I assure you, my dear friend, no one has expended so much labor on the study of composition as I have. There is hardly a famous master whose works I have not studied thoroughly and repeatedly."