Charles Spurgeon Commentary John 12:38-40

"that the word of Isaiah the prophet might be fulfilled, which he spake, Lord, who hath believed our report? And to whom hath the arm of the Lord been revealed? For this cause they could not believe, for that Isaiah said again, He hath blinded their eyes, and he hardened their heart; Lest they should see with their eyes, and perceive with their heart, And should turn, And I should heal them." — John 12:38-40 (ASV)

That the saying of Esaias the prophet might be fulfilled, which he spake, Lord, who hath believed our report? and to whom hath the arm of the Lord been revealed? Therefore they could not believe, because that Esaias said again, He hath blinded their eyes, and hardened their heart; that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them.

This passage is very frequently quoted in the Old Testament: it was so perfectly suited to the condition of the unbelieving Jews. They were willfully blinded. They could see it; they were forced to hear it; there was much that even touched their hearts; but they hardened their heart against it, and to this day they remain the same.