The prophecy that John references in the text (12:36-43) we are studying August 29, is from Isaiah 6.  We often think of that chapter as the "call of Isaiah" or the "Vision of God" and celebrate Isaiah's response..."Here am I, send me."  That was the right response but we may forget what kind of ministry God announced Isaiah would have!  It would not be one of perceived success, rather, his proclamation would only harden the hearts of those who were rejecting God's gracious provision.  This announcement of "judicial hardening" was not new.  We first learn of this with Cain and then with Esau and then with Pharaoh.  God did not predetermine the unbelief of these individuals but He finally gave them over to what they really wanted.  C.S. Lewis once wrote that people either say to God, "Thy will be done," or God says to people, "thy will be done."  We'd like to think that this hardening of the heart is only complete after death but the Scriptures seem to indicate that such a state is possible before we die.  Let us believe today that we do not become people with dull hearts, heavy ears and closed eyes.