Don't make reference to that of which we cannot speak.
Agreed, that which do not speak of is most certainly not to be spoken of or referenced to under any circumstances including, but not limited to:
I. the playing of that which we do not speak of
II. The talking of playing of that which we do not speak of
III. The thinking of playing of that which we do not speak of
IV. The thinking of talking about playing that which we do not speak of
V. The speaking of thinking about talking about playing that which we do not speak of
VI. The thinking.....okay you get the idea