Former US Defense Secretary Donald Rumsfeld has died at age 88

[silversurfer]

"...we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don't know we don't know...."

He was quoting someone else, not actually the nonsense politics some assumed but its misused arguably. The whole WMD deal was a con obvious at the time

https://en.wikipedia.org/wiki/There_are_known_knowns

What are unknown unknowns? Definition and examples (marketbusinessnews.com)

"Although the language may be tortured, the basic point is both valid and important."