Many forms of ignorance include the failure to recognize something that you experience.
There’s a scene in Michael Lewis’ book The New New Thing that chronicles a tear in a sail on Netscape investor Jim Clark’s mega yacht, the Hyperion. That ripped sail, way up on the 194-foot mast, stops the trip.
The Hyperion had at the time, the most advanced electronic monitoring and control systems. Yet, it took a crew member, a rare sailor among those on board, to notice a strange whipping sound, climb up the mast, and verify that the giant sail was ripping in the wind. While everyone on board was exposed to the same sound, few noticed that it was unusual. Fewer knew how to investigate and determine that the problem existed.