From a two year old blogpost…
As He passed by, He saw a man blind from birth. 2 And His disciples asked Him, “Rabbi, who sinned, this man or his parents, that he would be born blind?” 3 Jesus answered, “It was neither that this man sinned, nor his parents; but it was so that the works of God might be displayed in him. 4 We must work the works of Him who sent Me as long as it is day; night is coming when no one can work. 5 While I am in the world, I am the Light of the world.” 6 When He had said this, He spat on the ground, and made clay of the spittle, and applied the clay to his eyes, 7 and said to him, “Go, wash in the pool of Siloam” (which is translated, Sent). So he went away and washed, and came back seeing (John 9:1-7 NASB).
As evidenced by the question of the Disciples, many believed that every peculiar disaster faced by a person pointed to some special or particular sin. In fact, the historian Josephus records that some Jews believed that pious souls were reincarnated as a reward for a life well-lived. Pagan mysticism influenced many Jews of Jesus’ day, and there was much superstition as a result.
Jesus tells them that God was going to use this man’s blindness to make manifest His Power and Works.
The Spirit of the LORD is upon Me because He hath anointed Me to preach the Gospel to the poor; He hath sent Me to heal the brokenhearted, to preach deliverance to the captives, and recovering of sight to the blind, to set at liberty them that are bruised (Luke 4:18-19 KJV).
Source: I was blind, now I see