As a Shochet, Sofer, Mohel, teacher, etc. etc.
A personal story:
I recently attended a refresher course in a Jewish matter. I went for ulterior motives, as I already “knew” the material.
As I listened with half an ear, I quietly confirmed that I knew the course material perfectly. I could have taught better than the teacher. I noticed slight errors on his part, I could quote sources for everything, and I knew what he was going to say before he said it.
But that was all on the surface.
Under the surface, I realized that I wasn’t observing what I knew, even though I thought I was.
A word to the wise…