Now as Jesus passed by, He saw a man who was blind from birth.  And His disciples asked Him, saying, "Rabbi, who sinned, this man or his parents, that he was born blind?" 

Jesus answered, "Neither this man nor his parents sinned, but that the works of God should be revealed in him.  I must work the works of Him who sent Me while it is day; the night is coming when no one can work.  As long as I am in the world, I am the light of the world."

John 9:1-6   (NKJV)