Actually that known-unknown things is quite right and relevant.

Runsfeld didn't make it up - I read where someone chased up a philosophy text from which he'd lifted it. You've got to punctuate it properly, of course, and I think some newspapers had a bit of a problem there, because they don't normally worry too much about doing stuff like that.

And just imagine Bush trying to get through a sentence like that, even with an autocue...