Remind you of anyone?

"Therefore, I take it you asked him?"
"About the things I wanted to know, yes."
"And that included virtually everything?"
"Really, Mr. Mason, I could say as to that, because naturally I don't know how much I didn't know. I only know the things I did know."
The Case of the Golddigger's Purse, Erle Stanley Gardner, 
Pocket Book edition, 1951, p. 126.