Even when we're standing at the door holding the key, we find that there's a particular way of turning it - a special flick of the wrist - that we need to learn.

Metalanguages ...

The one above the one we're using - in which a theory of truth for our language could be formulated - cannot be translated, and, so, cannot be recognised as a language ...

The one below, which we can give an account of, is reduced to syntax, rules, and symbols. It's meaning has been relegated to 'interpretation' and lost to truth-telling. Is it a language or a board game?

Neurath's Boat

It isn's just the planks and frames that keep the boat afloat, but also the conceptions of the sailors: their plans of the boat, their principles of naval architecture, the epistemological foundations of both ...

Which is why they can never have a complete design, never mind do a complete rebuild.