The disciples assumed that suffering must be someone's fault, and they wanted to know whose. Barnes explains, "It was a universal opinion among the Jews that calamities of all kinds were the effects of sin." But this man was born blind, which made the puzzle harder. Could he have sinned before birth? Barnes says some Jews believed "an infant might sin before it was born," and others that "the crime of the parent might be the cause of deformity in the child." Gill suggests the first option may have come either from the idea of souls passing into other bodies or from the belief that a child could sin in the womb. Matthew Henry thinks the question was both uncharitable toward the man and more curious than useful.

Jesus rejected both options: "Neither hath this man sinned, nor his parents: but that the works of God should be made manifest in him" (John 9:3). He added, "I must work the works of him that sent me, while it is day," and "I am the light of the world" (John 9:4-5). Then He made clay, anointed the man's eyes, and said, "Go, wash in the pool of Siloam." The man "went his way therefore, and washed, and came seeing" (John 9:6-7).

Jesus faced the same assumption elsewhere. When people told Him of Galileans killed by Pilate, He asked, "Suppose ye that these Galilaeans were sinners above all the Galilaeans, because they suffered such things?" (Luke 13:2). Barnes points to that passage here.

Later in the same chapter, the Pharisees voiced the same belief about this man, telling him, "Thou wast altogether born in sins" (John 9:34).

This question shows that God's purposes in suffering are bigger than our explanations. The disciples looked for someone to blame. Jesus looked for what God would do. Matthew Henry writes, "Christ says of uncommon calamities, that they are not always to be looked on as special punishments of sin; sometimes they are for the glory of God, and to manifest his works."

Jesus did not stop at an answer. He went to work, because He is "the light of the world" (John 9:5). Henry notes, "This poor man could not see Christ, but Christ saw him." Barnes draws a lesson for us: "To pity and not to despise and blame those who are afflicted." He also writes, "All suffering in the world is not the effect of sin," which leaves room for the truth that some suffering is, while forbidding us to assume it.