Who played the keyboard with striking virtuosity?
Nannerl herself was an   apt pupil, no less quick to learn than her brother, and was playing the keyboard with striking virtuosity by the time she was eleven. In that year, 1762, Leopold brought the children to Munich to play before Maximilian III Joseph, Elector of Bavaria. Leopold then took the entire family to Vienna, on a trip that lasted for three months. He had secured invitations from several noble patrons, and within three days of arriving the children were playing at the palace of Count Collalto. Among those present was the Viennese Treasury councillor and future prime minister Karl von Zinzendorf, who noted in his diary that "a little boy, said to be only five-and-a-half years old [Wolfgang was actually nearly seven], played the harpsichord". After an appearance before the Imperial Vice-Chancellor, the Mozarts were invited to the royal court, where the Empress Maria Theresa tested Wolfgang's abilities by requiring him to play with the keyboard covered. During this court visit Wolfgang met the Archduchess Maria Antonia, the future Queen Marie Antoinette of France, who was two months his senior. Mozart's biographer Eric Blom recounts an anecdote of how the Archduchess helped Wolfgang when he slipped on the polished floor; she is supposed to have received a proposal of marriage in return.As the Mozarts began to be noticed by the Viennese aristocracy, they were often required to give several performances during a single day. They were well rewarded for this activity—at the end of their first hectic week in Vienna, Leopold was able to send home the equivalent of more than two years' salary. Their schedule was interrupted when Wolfgang fell ill with scarlet fever, and their former momentum was not regained. Nevertheless, the visit left Leopold eager to pursue further opportunities for social and financial success. On their return to Salzburg, Wolfgang played the harpsichord and violin at a birthday concert for the archbishop, to the evident astonishment of those present.
Wolfgang