I have oft quoted, on this blog, and in countless presentations, from The Looming Tower:  Al-Queda and the Road to 9/11 by Lawrence Wright (winner of the Pulitzer Prize, 2007).  And Inside the Kingdom by Carmen Bin Laden.

Here is s link to a reading list, all books that were highlighted on PBS, with links to interviews with the authors:  A Reading List for the Post-9/11 Era, posted by Molly Finnegan , May 3, 2011.  From the intro:

The NewsHour has featured conversations with many writers over the past decade on books that address, directly and indirectly, how 9/11, bin Laden and the wars in Iraq and Afghanistan have influenced how we live today. After the jump, find a sampling of some of these featured titles with links to the full conversations.

The list is a good one, and, yes, it includes The Looming Tower.  Here is the quote lifted from the full interview (link on the page) with Wright on the book list page:

From the conversation:
“Humiliation is one of the most common words in bin Laden’s vocabulary. Certainly there have been many Muslim men who have been physically humiliated, especially Arabs and Egyptians in those prisons. For instance, Ayman al-Zawahiri, the number two guy in al-Qaida, experienced three years of torture in Egyptian prisons, as was true of many people who are in al-Qaida today. I think that accounts for the appetite for bloodshed that’s so characteristic of al-Qaida and so unusual in many respects for a terrorist movement, which is normally just interested in theater….When he uses that term, it resonates with many Muslims who feel that Islam has been in retreat for hundreds of years and been displaced from his proper place in the world.”