When Leopold was arranging the publication of his treatise on musical instruction, Violinschule, with Johann Jakob Lotter, a friend and printer in his home town of Augsburg. He broke the good news to Lotter in a letter that February 9: ". . . I must inform [you] that on 27 January, at 8 p.m., my dear wife was happily delivered of a boy; but the placenta had to be removed. She was therefore astonishingly weak. Now, however (God be praised) both child and mother are well. She sends her regards to you both. The boy is called Joannes Chrisostomos, Wolfgang, Gotlieb."
On the Roman Catholic calendar, January 27 belonged to St. John Chrysostom, Patriarch of Constantinople and patron saint of orators. Gotlieb is "beloved of God"; in Latin, Amadeus. Wolfgang was in honor of his maternal grandfather, Wolfgang Nikolaus Pertl. As a grown man he would sign himself "Wolfgang Amadé Mozart," or just "Mozart." But for now he was b3a Wolfgang, or more affectionately, "Wolfgangerl."
Not much is known of Wolfgang’s very early life. Probably, his father concentrated on his court career and on teaching. Certainly he tutored Maria Anna, who the family called Nannerl. When she reached the age of seven, Leopold began to instruct her on the clavier -- and soon discovered to his keen satisfaction that she had a gift for music. He continued the girl’s studies, challenging her with a series of exercises that he wrote out for her in a notebook that he titled Pour le clavecin, ce Livre appartient à Mademoiselle Marie-Anne Mozartin 1759.
The boy’s curiosity was piqued as well. As Nannerl later recalled, the three-year-old Wolfgang "often spent much time at the clavier, picking out thirds, which he was always striking, and his pleasure showed that it sounded good."
Recognizing his childrens’ special abilities, Leopold began to devote extra effort to their educations -- with an emphasis on musical instruction. He became a loving, but exacting, taskmaster. Some time later, he would somewhat ruefully describe to a correspondent how from a very early age Nannerl and Wolfgang had learned to wear the "iron shirt" of discipline. The children themselves probably never realized that life could be any different. Wolfgang, no doubt, enjoyed the extra attention and found great pleasure in learning -- and in pleasing his father. It was the start of a relationship that he would never quite break free of, and the beginning of a career that would consume him altogether.