"No, no, no!" That is the response that you get when you ask EU players whether they can abandon the principles that are determining their stance on Brexit.

The response you get when you ask UK insiders whether they can move on their core beliefs about Ireland. "No, no, no!".

And guess what, for more than two years now people involved in the Brexit process have been saying, ah, until we can find a way through on the question of Ireland well, we can't be sure of anything.

Sure, there is a huge amount of chatter about how some nips and tucks to the rival proposals might change things, to soften the hard edges of the arguments.

The UK might accept a border for rules and regulations in time, but there is no chance that as things stand, they will go anywhere near touching a different customs system for Northern Ireland.

The EU might come up with cunning plan after cunning plan, asking for only one kind of check, or a system rather like the one that operates between Spain and the Canary Islands.

Every single comment made by Michel Barnier is examined in microscopic detail to see what compromise it might reveal.

Here's the thing. The disagreements aren't over the detail, it's not the practicalities that are really the problem but the principles.

Officials involved privately admit there is little chance that the solution is going to be found in any of the technical solutions, there is going to have to be a big political move on one side, or moves on both sides to be able to get to a deal.

And despite protestations from Brexiteers about how Ireland has come to dominate the talks, it has become whether they like it or not, the real life expression of Brexit's bigger conundrums.

The talks were always going to be complicated. But summit after summit, the biggest obstacle remains what happens there after we leave the EU.

Because after Brexit the border between Northern Ireland and the rest of the island becomes the line between the huge European trading club and a country that's on the outside.

No one wants there to be anything that really changes or disrupts life on either side. But Brexit is such a major change that everything simply can't remain the same. The two sides in the negotiations seem stuck in a deep clash over how to handle the change.

Because the EU has more power in the negotiations it's often assumed that the UK will end up having to ditch its resistance. And with some soft soaping from Brussels around the language of their proposals Theresa May will just about be able to swallow more compromises.

But ahead of the Tory conference, rather than showing any flexibility the UK is sticking with its position.

The PM appealed to the other EU leaders on Wednesday, imploring them to understand that she can't accept what's on the table right now. But with a rough date set for deal day, the position might have to evolve.

And Wednesday's digging in might make any eventual climbdown more painful still, yet the prime minister may not find herself with that much choice.

After all, the answer she can't accept for the whole deal in the end, is, "no, no, no!"