He was composing by the age of five and is well-known across the world as an influential music figure.
could be that we're still playing his pieces today...
that makes him a genius to me:-)
A couple of stories.
When attending a performance as a little boy, (his father would bring him along), he walked across the stage before the curtains opened and informed one of the violinists that his instrument was an eighth tone sharp.
On a trip to another town for a performance of one of his overtures which he had recently written, the manuscript was lost. He had to scramble madly to re-write the overture and had something like one day to do it. Long after the performance was over and Mozart had left town, somebody found the lost manuscript and noticed something interesting. He compared it to the one Mozart hurriedly wrote and the two were absolutely identical. Every note, every rest, every dynamic and notation.
When he was ten, heard an opera for the first time and later wrote to a friend about an aria he liked. He wrote the entire aria, accurately, from memory after hearing it only once.
He apparently wrote the entire Haffner symphony in six days, without ever once going to the keyboard.
Not only was Mozart perhaps the best pianist in Europe in his day, but many don't realize he was also one of the top three or four violinists.
He composed his marvelous 25th symphony in G-minor when he was 17. (How old must he have been for the previous 24?!) For anyone reading this, if you aren't familiar with it, it is the one played during the opening credits of Amadeus. One who loves Mozart really should listen to the whole thing sometime. I just cannot picture a boy, barely past pimples, writing something like that.
If those examples aren't prodigious genius, I don't know what is.