The only thing we know is what we don't know..

You are on the right track, Robert.

Socrates said:

- As for me, all I know is that I know nothing.

That's not the exact one I was looking for but it brought me to it (also attributed to Socrates):

I know nothing except the fact of my ignorance.

Thanks!

That's the same one, it's just a matter of translation from Greek:

I know that I know nothing

Turns out some think he didn't say it:

The Skeptic scroll down to the Article

I am ignorant of so much, but I haven't anyway of gauging the depth of my ignorance.

Joe(A boater on a murky pond)Nation

I didn't find substantiation to that in the link, but I only glossed. Before seeing Joe's article I had serious doubts about these quotes attributed to him. I suspect the variations are the result of misattribution more so than translation.

Off base, but I like this version.

The more I know, the less I knew.