This was to fulfill the word spoken by the prophet Isaiah: "Lord, who has believed our message, and to whom has the arm of the Lord been revealed?"
And so they could not believe, because Isaiah also said,
"He has blinded their eyes and hardened their heart, so that they might not look with their eyes, and understand with their heart and turn— and I would heal them."
Isaiah said this because he saw his glory and spoke about him.
References for John 12:41