Jesus said to a blind man,
“As long as I am in the world, I am the light of the world” (John 9:5),
referring to spiritual light.
Then to help that man understand that Jesus can help us to see in the spirit, He healed the man of his bodily blindness,
“When He had said these things, He spat on the ground and made clay with the saliva; and He anointed the eyes of the blind man with the clay” (John 9:6).
Jesus did not come primarily to give sight to the biologically blind, but He did do such miracles that we might understand how He can give us sight in the spirit.