Best Answer: I think Bach was Blind the last year of his life due to a failed eye surgery. Kuhlau feel on a stick in a forest while he was running on lost one of his eyes too!! It happened when he was young. Beethoven went deaf shortly after he wrote his 3rd symphony Some people thought Beethoven was insane because he talked loudly because of his hearing loss. People thought Mozart went insane after the death of his father. I am sure alot of people thought Bartok was insane because no one understood his music at the time.