Even the successes of "Don Giovanni," which was received with thunders of applause, failed to remedy his desperate financial straits. Shortly after this his pupil and patron, Prince Karl Lichnowsky, proposed he should accompany him to Berlin. Mozart gladly consented, hoping for some betterment to his fortunes. The King of Prussia received him with honor and respect and offered him the post of Capellmeister, at a salary equal to about three thousand dollars. This sum would have liberated him from all his financial embarrassments, and he was strongly tempted to accept. But loyalty to his good Emperor Josef caused him to decline the offer.
The month of July, 1791, found Mozart at home in Vienna at work on a magic opera to help his friend Salieri, who had taken a little theater in the suburb of Wieden. One day he was visited by a stranger, a tall man, who said he came to commission Mozart to compose a Requiem. He would neither give his own name nor that of the person who had sent him.
Mozart was somewhat depressed by this mysterious commission; however he set to work on the Requiem at once. The composing of both this and the fairy opera was suddenly interrupted by a pressing request that he would write an opera for the coronation of Leopold II at Prague. The ceremony was fixed for September 6, so no time was to be lost. Mozart set out at once for Prague. The traveling carriage was at the door. As he was about to enter it, the mysterious stranger suddenly appeared and enquired for the Requiem. The composer could only promise to finish on his return, when hastily entering his carriage, he drove away.
The new opera, "La Clemenza di Tito," was finished in time and performed, but was received somewhat indifferently. Mozart returned to Vienna with spirits depressed and body exhausted by overwork. However, he braced himself anew, and on September 30th, the new fairy opera, the "Magic Flute," was produced, and its success increased with each performance.
The Requiem was not yet finished and to this work Mozart now turned. But the strain and excitement he had undergone for the past few months had done their work: a succession of fainting spells overcame him, and the marvelous powers which had always been his seemed no longer at his command. He feared he would not live to complete the work. "It is for myself I am writing the Requiem," he said sadly to Constanza, one day.