is an excellent book by Piero Melograni (isbn 0-226-51961-9). As usual I'm going to quote from a few pages:
Mozart was great (among other reasons) because he knew how to have fun.
Some people believe that music flowed from him almost spontaneously, thanks to his genius. In reality, from earliest childhood he practiced for thousands of hours every year.
He lived only thirty-five years, but he lived them at a wolf's pace and went far in that short time.
In a letter dated 20 August 1763, Leopold Mozart relates that in many places in Germany the well water was so bad, smelly, and muddy that it was habitually mixed with wine. It was worse in Paris. Parisians drank the repugnant water of the Seine, into which the city's garbage was thrown. The Mozarts, like many others, let it settle in a pitcher for a few hours, where it formed a worrisome solid layer.
In a letter dated 1 April 1764 Leopold reported that when an eclipse of the sun had occurred, Parisians rushed into the churches to protect themselves from being poisoned by the air during the temporary disappearance of the sun's light.
Wolfgang fell seriously ill with smallpox. He was blind for nine days and hovered between life and death, for the second time, after his bout with typhus in 1765.
Mozart performed several times on the harpsichord, astonishing his listeners with the agility of his hands, his left hand in particular. Some Neapolitans, perhaps influenced by a culture that tended to superstition and like mysteries. asserted that the boy played as well as he did thanks to a magic ring that he wore. When they demanded that he take off the ring and play without it, they saw that his playing depended on talent rather than spells, and they applauded all the more.
In those days, a composer would not dream of writing the arias for an opera without consulting the singers who were to interpret them… composers were craftsmen, paid by the piece, and were completely subservient to the true superstars of the age, who were the singers.
In those days no one hesitated about applauding in the middle of a work of music.
His fingers were deformed, either because of continual keyboard exercises from childhood on or from arthritis.
Only artists capable of innovation can give a long life to their works. Innovation prompts tension, curiosity, and awe.