If at first you don't succeed you can try and try.

But eventually, sometimes, failure is what follows.

There is a chance still that a couple of frantic days could result in a change.

The prime minister could decide that after all, the potential disruption of no deal is just too great to risk.

The EU president might be able to persuade continental leaders to budge, as they gather in Brussels today.

But the chance of reassessing and refreshing the efforts seem now remote.

The talks between Boris Johnson and Ursula von der Leyen were difficult - the gaps between them no slimmer at the end than the start.

The hoped-for mutual understanding, the nudge or wink to pursue compromise, did not come.

The only agreement was on when they might call a halt.

For the first time in a world of highly moveable deadlines, they announced that a final decision must be taken by the end of the weekend.

Both sides want to stick to their principles. But that determination right now has set them on the path to the practical outcome they both wanted to avoid - and, if nothing changes, the chance of significant disruption at least in the short term for the country in many different ways.

And for both sides, failing to agree would be a real political accident - something they don't want, and that didn't have to happen.

One diplomat told me: "It's dystopian - the UK wants to have the absolute freedom to do things it will probably never do - apart from some tinkering. The EU wants to protect itself from things that will probably never come."

People involved in the negotiations believed that there was a way through that could protect each part.

But unless one side, or more likely both, aren't willing to give up some of their principles very fast, or the negotiators come up with a sudden miracle, then for all his optimism, Boris Johnson may fail to achieve the trade deal that Brexiteers boasted would be easy.

A result that he always said he would be ready for, but no doubt what he wanted to avert.

BBC