The disciples wondered 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. (John 9:2, 3 NKJV). 

And here we see 2 major facts

1.the cross is one of life's prerequisites  and pain is an important necessity we can't avoid..and no one can escape from it  . For both the saint and the sinner suffers pain ,Jesus Himself was not exempted for in that He Himself has suffered, being tempted,(Hebrews 2:18 NKJV)

2. That pain does not stand alone 

For there are salvation benefits for this pain and God glorifies within it.

The man born blind had pain( the bitter truth) but there was another truth revealed by Lord Jesus when He said"the works of God should be revealed in him"when the light of God shed on this blind man and kicked darkness out..and the work of God revealed by this miracle.

"And we know that all things work together  for good ( including pain) to those who love God, (Romans 8:28 NKJV)