There are the known unknowns and the unknown unknowns.
On April 10th, 2019. See this statement in context.
On April 10th, 2019. See this statement in context.
April 10th, 2019 / 4:25 p.m.
Director, Office of the Chief Information Officer, Amazon Web Services, Inc.
There are the known unknowns and the unknown unknowns.
See context to find out what was said next.