It is so easy to think you're right when you're wrong; to over-estimate one's own knowdlege or understanding. It's good to remind yourself of this frequently.

Is this like the Donald Rumsfeld statement about known unknowns compared to unknown unknowns? But lest we forget the unknown knowns and the known knowns as they are also part of the equation

Yes. This leads to "eating crow"; my least favorite dish. If I'm not 100% sure, I tend to preface my posts with "I believe" or post some other form of disclaimer.

Yes...I can get with that! And after you learn, what you think is a lot...you see that is only the tip of the ‘iceberg!’

GOOD ONE! That ranks right up there with the challenge of remembering things as well as you once did.