By Robert Chambers
This text is an excerpt from the entry for December 5th from Robert Chambers’ Book of Days: A Miscellany of Popular Antiquities in Connection with the Calendar, including Anecdote, Blog, and History, Curiosities of Literature and Oddities of Human Life and Character. This book was first published in 1864 with additional editions published later. It is now in the public domain. Amos-Cola Staff has added images, links, and notes.
Mozart appears as a being eccentrically formed to be a medium for the expression of music and no grosser purpose. In this he was strong: in everything else of body and mind, he remained a child during the thirty-six years to which his life was limited.
When three years old, his great amusement was finding concords on the piano; and nothing could equal his delight when he had discovered a harmonious interval. At the age of four, his father began to teach him little pieces of music, which he always learned to play in a very short time; and, before he was six, he had invented several small pieces himself, and even attempted compositions of some extent and intricacy.
‘The sensibility of his organs appears to have been excessive. The slightest false note or harsh tone was quite a torture to him; and, in the early part of his childhood, he could not hear the sound of a trumpet  without growing pale, and almost falling into convulsions. His father, for many years, carried him and his sister  about to different cities for the purpose of exhibiting their talents. In 1764, they came to London, and played before the late king [3.]. Mozart also played the organ at the Chapel Royal; and with this the king was more pleased than with his performance on the harpsicord. During this visit he composed six sonatas, which he dedicated to the queen . He was then only eight years old. A few years after this he went to Milan; and at that place was performed, in 1770, the opera of Mithridates , composed by Mozart at the age of fourteen, and performed twenty nights in succession. From that time till he was nineteen, he continued to be the musical wonder of Europe, as much from the astonishing extent of his abilities, as from the extreme youth of their possessor.
‘Entirely absorbed in music, this great man was a child in every other respect. His hands were so wedded to the piano, that he could use them for nothing else: at table, his wife carved for him; and, in everything relating to money, or the management of his domestic affairs, or even the choice and arrangement of his amusements, he was entirely under her guidance. His health was very delicate ; and, during the latter part of his too short life, it declined rapidly. Like all weak-minded people, he was extremely apprehensive of death; and it was only by incessant application to his favourite study, that he prevented his spirits sinking totally under the fears of approaching dissolution. At all other times, he laboured under a profound melancholy , which unquestionably tended to accelerate the period of his existence. In this melancholy state of spirits, he composed the Zauberflöte , the Clemenza di Tito, and the celebrated mass in D minor, commonly known by the name of his Requiem. The circumstances which attended the composition of the last of these works are so remarkable, from the effect they produced upon his mind, that we shall detail them; and, with the account, close the life of Mozart.
One day, when his spirits were unusually oppressed, a stranger, of a tall, dignified appearance, was introduced. His manners were grave and impressive. He told Mozart that he came from a person who did not wish to be known, to request he would compose a solemn mass, as a requiem for the soul of a friend whom he had recently lost, and whose memory he was desirous of commemorating by this solemn service. Mozart undertook the task, and engaged to have it completed in a month. The stranger begged to know what price he set upon his work, and immediately paid him one hundred ducats, and departed. The mystery of this visit seemed to have a very strong effect upon the mind of the musician. He brooded over it for some time; and then suddenly calling for writing materials, began to compose with extraordinary ardour. This application, however, was more than his strength could support; it brought on fainting fits; and his increasing illness obliged him to suspend his work. “I am writing this Requiem for myself! ” said he abruptly to his wife one day; “it will serve for my own funeral-service; ” and this impression never afterwards left him. At the expiration of the month, the mysterious stranger appeared, and demanded the Requiem. ” I have found it impossible,” said Mozart, “to keep my word; the work has interested me more than I expected, and I have extended it beyond my first design. I shall require another month to finish it.” The stranger made no objection; but observing, that for this additional trouble it was but just to increase the premium, laid down fifty ducats more, and promised to return at the time appointed. Astonished at his whole proceedings, Mozart ordered a servant to follow this singular personage, and, if possible, to find out who he was: the man, however lost sight of him, and was obliged to return as he went. Mozart, now more than ever persuaded that he was a messenger from the other world, sent to warn him that his end was approaching, applied with fresh zeal to the Requiem; and, in spite of the exhausted state both of his mind and body, completed it before the end of the month. At the appointed day the stranger returned; but Mozart was no more. 
[1.] “Until he was almost nine he was terribly afraid of the trumpet when it was played alone … Merely to hold a trumpet in front of him was like aiming a pistol at his heart,” according to family friend and biographer Johann Andreas Schachtner.
[2.] Maria Anna Mozart, also known as Marianne and Nannerle, (1751-1829) was a gifted musician and music teacher. It was said that her younger brother idolized her and that the two developed a secret language and imaginary kingdom, the ”Kingdom of Back” which they shared. The young Wolfgang wrote pieces for his sister to perform and was inspired in his musical studies by watching his older sister study and work at the craft before him. See Wikipedia, Mozart’s Sister (film), Smithsonian Magazine. (More scholarly sources available; check your public or university library database.)
[3.] Mozart and his sister played for King George III and his wife, Queen Charlotte, in April, 1764.
[4.] Mozart’s Violin Sonatas, KV10-15, were commissioned by Charlotte on the 25th of October, 1764, and dedicated to her in January of 1765.
[5.] See also Fayard, Judy: ”Though He Wrote It at 14, Mozart’s ’Mitridate’ Is A Very Serious Opera” (Wall Street Journal)
[6.] See also Karhausen LR. The Myth of Mozart’s Poor Health and Weak Constitution. Journal of Medical Biography. 1999;7(2):111-117. doi:10.1177/096777209900700207
[7.] See Huguelet P, Perroud N. Wolfgang Amadeus Mozart’s psychopathology in light of the current conceptualization of psychiatric disorders. Psychiatry. 2005;68(2):130-9. doi: 10.1521/psyc.2005.68.2.130. PMID: 16247856.
[8.] Die Zauberflöte (The Magic Flute). Synopsis here.
[9.] This narrative has been immortalized in Thornton Wilder’s play ”Mozart and the Gray Steward,” among other works. Obviously the play and movie ’Amadeus’ propound the ”Salieri” theory that Salieri was the commissioner of the Requiem and the murderer of Mozart, but this is good drama and bad history. While it is unclear who commissioned the Requiem (we think), it is most likely Mozart died from a staph infection.