Task: Question Answering
Input (English): Passage: George Frideric Handel was born on 23 February 1685 in the German city of Halle. It is unclear what initial musical education he received; his father, Georg Händel, was not a music lover, and did not at first appreciate or encourage his son's precocious talents. Nevertheless, by the age of ten Handel had become an accomplished organist; his playing in the royal chapel at Weissenfels, where his half-brother Karl was in the service of the Duke of Saxe-Weissenfels, impressed the duke, who persuaded Händel senior that the boy should have a proper musical education. As a result, Handel began formal study under Friedrich Zachow, the organist of the Lutheran church at Halle.Handel's biographer Jonathan Keates writes that: "From [Zachow] Handel learned not only a great deal about the line and shape of an aria, about strong, adventurous bass lines and solid choral writing, but also about those delicacies of instrumental colouring which he later perfected in his own style". Handel's musical development also benefited from an early and lasting friendship with Georg Philipp Telemann, whom he met in 1700. In February 1702 Handel enrolled at the University of Halle, perhaps intending to study law. In March he took up the post of organist at Halle's Calvinist cathedral (Domkirche), a prestigious appointment for one so young and indicative of his burgeoning musical reputation in the city.At some time, possibly in late 1702 or early 1703, Handel visited Berlin, where his father had held an honorary post as physician to the elector who, in 1701, had become the Prussian king Frederick I. In Berlin Handel first experienced Italian opera, and may have met the Italian composers Giovanni Bononcini and Attilio Ariosti, who were writing operas for Frederick's court. The king heard of Handel's abilities, and wanted him to train as a future court composer, but Handel's horizons had been broadened by his sojourn in Berlin and he was developing his own ideas for his future. He declined the king's offer, and returned to Halle to fulfil his year's contract at the Domkirche. With few career prospects available in his home city, Handel would have liked to go to Italy, but this, he realised, was not yet practicable, since he lacked both cash and contacts. Instead in mid-1703 he left Halle for Hamburg, a thriving free city which housed the leading opera house in northern Germany. 
Question: Who impressed the Duke of Saxe-Weissenfels when they were 10?
Output (English): George Frideric Handel.