What is the proof that I know something? Most certainly not my saying I know it. - Ludwig Wittgenstein

Our language can be seen as an ancient city: a maze of little streets and squares, of old and new houses, and of houses with additions from various periods; and this surrounded by a multitude of new boroughs with straight regular streets and uniform houses.

The form is the possibility of the structure.

Telling someone something he does not understand is pointless, even if you add that he will not be able to understand it. (That so often happens with someone you love.)
If you have a room which you do not want certain people to get into, put a lock on it for which they do not have the key. But there is no point in talking to them about it, unless of course you want them to admire the room from outside!
The honourable thing to do is to put a lock on the door which will be noticed only by those who can open it, not by the rest.