Does anybody know the origin of the saying that begins, "There is something that you know that I don't know."?

This is a poem bu R.D. Lang

There is something I don't know that I am supposed to know.

I don't know what it is I don't know and yet am supposed to know, and I feel I look stupid if I seem both not to know it and not know what it is I don't know.

Therefore I pretend I know it.

This is nerve-racking since I don't know what I must pretend to know.

Therefore I pretend to know everything.

I feel you know what I am supposed to know but you can't tell me what it is because you don't know that I don't know what it is.

You may know what I don't know, but not that I don't know it,

and I can't tell you. So you will have to tell me everything.

The idea is close to this from Ralph Waldo Emerson:

"Every man I meet is my superior in some way. In that, I learn from him."

Its origins are based on the concept that there is always more to learn than there is to teach !!