John 12:37–40 (NKJV)
37 But although He had done so many signs before them, they did not believe in Him, 38 that the word of Isaiah the prophet might be fulfilled, which he spoke: “Lord, who has believed our report? And to whom has the arm of the Lord been revealed?” 39 Therefore they could not believe, because Isaiah said again: 40 “He has blinded their eyes and hardened their hearts, Lest they should see with their eyes, Lest they should understand with their hearts and turn, So that I should heal them.”
This is a sad commentary on the people who witnessed firsthand the signs and teachings of the Messiah. But this is just what Isaiah had predicted in Isaiah 6 and in Isaiah 53. But John's next comment reveals the glory - God's intentions are never thwarted by man's rebellion -
John 12:41 (NKJV)
41 These things Isaiah said when he saw His glory and spoke of Him.
Of course, John is referring particularly to the vision Isaiah had of the Lord in Isaiah 6. That is the center of the first section of Isaiah, chapters 1-12. Chapter 6 is the center of the chiastic structure and so the main idea of the section - the glory of God revealed. And while 1-12 are filled with judgments, both upon Judah and Israel - it is chock full of promises of God's salvation despite their rejections. Chapter 12 ends it all beautifully and hopefully -
Isaiah 12:1–2 (NKJV)
1 And in that day you will say: “O Lord, I will praise You; Though You were angry with me, Your anger is turned away, and You comfort me. 2 Behold, God is my salvation, I will trust and not be afraid; ‘For Yah, the Lord, is my strength and song; He also has become my salvation.’ ”
And so, in John's gospel, the passion begins - and the glory of the Lord will be revealed in the cross and resurrection.