Know What You Don't Know by Michael Roberto

Roberto goes beyond shoe-horning examples into supporting his notions; when the generally accepted facts don't fit, he straps them into his own Procrustean bed.

The story of the Son Tay raid highlights a very important challenge for leaders in all organizations. People at various levels in the organizational hierarchy filter information for various reasons.
-- Circumvent the Gatekeepers
Son Tay is not a canonical example of filtering communication; rather it shows a failure to use technology and organizational command to tighten a force's reaction time ( OODA loop ).
"What really grabbed our attention was another pile of rocks that had been laid out in Morse code that said there were at least six men in that prison (Son Tay) who were going to die if they didn't get help fast."
Special-operations forces trained rigorously for this mission, rehearsing a remarkable one hundred seventy times in the months leading up to the raid.
-- Circumvent the Gatekeepers

Furthermore, when Roberto talks about the unknown, he means exploring the precursors of failure (look at yourself, your team, your tools, your field of work). However, classifying the unknown into parts we can map and parts we can't is just the first step. What do we do with the all the stuff that's not even on the map?

So, Roberto punts on the problem of the unknown, which should at least raise questions like: What classes of unknown events do you care about? Can you self-insure against them? Is it even worth it?