Josef Mysliveček was born in Prague on 9 March 1737, one of twin sons of a prosperous mill owner, studied philosophy at Charles-Ferdinand University and took the rank of master miller in 1761 before giving up the trade for music. He studied composition in Prague with Franz Johann Habermann and Josef Seger, and in 1763 went to Venice to work with Giovanni Battista Pescetti, his journey paid for partly from family money and partly by the Bohemian nobleman Vincenz von Waldstein. In Italy he was known as Il Boemo, the Bohemian; the more famous Il divino Boemo comes from the title of a novella about him published by Jakub Arbes in 1884, not from his lifetime. He was elected to the Accademia Filarmonica di Bologna in 1771, never took service with any noble or prelate — unusually for his generation — and lived by teaching, playing, composing and the gifts of wealthy admirers. He died on 4 February 1781.

He gave the young Mozart working models in three genres — the symphony, Italian opera seria and the violin concerto — and both Wolfgang and Leopold counted him a close friend from their first meeting in Bologna in 1770 until he broke their trust over a promised commission at the Teatro di San Carlo, an episode that runs through the family correspondence. His first opera, Semiramide, was staged at Bergamo in 1766, and Il Bellerofonte, premiered at San Carlo on 20 January 1767, was a large enough success to bring commissions from theatres across Italy; from then on his operas were cast with first-rank singers and were almost always successful, until Armida failed at La Scala in the 1780 carnival season. Apart from a visit to Prague in 1768, a short one to Vienna in 1772 and a stay in Munich from December 1776 to April 1778, he never left Italy after 1763.

Sources:

• https://en.wikipedia.org/wiki/Josef_Myslive%C4%8Dek
• https://www.wikidata.org/wiki/Q313974