Should be:
"You know not of (that) which you speak (of)..."
or
"You know naught of what you speak (of)..."
That's right, I'm Noam Chomsky!
This gracious grammatical interlude brought to you by the letter "g".
These two were a real hoot none-the-less.
I'm looking forward to their response.
Think FreeTally will finally admit this single point of debate?