Who is Carl Czerny from The Great Pianists and what is their importance?

Carl Czerny was one of the greatest pianists who never played in public. Because he disliked travel he stayed in Vienna teaching pupils and composed a thousand published works. Born in 1791 Vienna, he worked with Beethoven and got a letter of recommendation from him in 1805. Czerny taught many great pianists including Liszt, Dohler, Kullak and Leschetizky who also taught many students of their own, which multiplied Czerny's importance and influence. Towards the end of his career he played with Chopin who called him a good fellow but not more.