Chayei Sarah - Accessing Revelation

What follows when a great righteous individual dies? How did this spiritual void express itself after the death of Avraham, Moshe, Yehoshua and Shaul? How does this parallel the fact that Yitzchak had to re-dig the wells that his father Avraham had previously dug that had become stopped up? What was the mistake of the nations of the world as regards Hashem's intimate interactions with mankind that Avraham corrected? What initiated the withdrawal of Hashem's Divine Presence from the world, and how was it brought back from the time of Avraham and on through Moshe?