You do not really understand something unless you can explain it to your grandmother

I can explain it for you, but I can't understand it for you

The more you explain it, the more I don't understand it.

The older I get, the more I believe in what I can't explain or understand, even more than the things that are explainable and understandable.

Please explain the problem to me slowly, as I do not understand things quickly.

It's among the intelligentsia that we often find the glib compulsion to explain everything and to understand nothing.