As he passes by, Jesus sees a man blind from birth. The disciples ask who sinned, the man or his parents, that he was born blind. Jesus answers that it was not the sin of either, but so that the works of God might be displayed in him. He says that as long as he is in the world he is the light of the world. He spits on the ground, makes mud, puts it on the blind man's eyes and tells him to wash in the pool of Siloam. The man obeys and returns seeing. His neighbors doubt it is the same man, but he insists and tells what Jesus did.
They bring him to the Pharisees, because it was the Sabbath when Jesus made the mud. The Pharisees are divided: some say Jesus is not from God because he does not keep the Sabbath; others ask how a sinner can do such signs. They ask the man what he thinks of Jesus, and he answers that he is a prophet. The Jews do not believe he was blind and call his parents, who confirm that he is their son and was born blind, but for fear of being put out of the synagogue they refer the matter to him.
They call the man a second time and tell him to give glory to God, since they know Jesus is a sinner. He answers that one thing he knows: he was blind and now he sees. When they press him, he asks them with irony whether they want to become Jesus' disciples, and argues that if this man were not from God he could do nothing. They insult him and drive him out.
Jesus finds him and asks whether he believes in the Son of Man. The man asks who he is, and Jesus tells him that he is looking at him and that it is the one speaking with him. The man says he believes and worships him. Jesus says he came into this world for judgment, so that those who do not see may see and those who see may become blind. Some Pharisees ask whether they are blind too, and Jesus answers that if they were blind they would have no guilt, but because they say they see, their guilt remains.