Junior doctors' dispute: Who will break first?
Two things have become clear during the first ever all-out doctors' strikes. One, with good planning hospitals can cope for a few hours without junior doctors.
And, two, this is going to be a fight to the bitter end. While consultants and nurses were stepping into the void left by the striking junior doctors, both sides have been briefing about how determined they are not to give ground.
But who will break first? Ministers or doctors?
The government now sees this as a point of principle which it cannot lose. They have been telling journalists how they believe elements in the British Medical Association have made this into a political strike. Their goal? To force the dismissal of Health Secretary Jeremy Hunt and the fall of the entire government, sources say.
Some have even likened it to this government's miners' strike moment. They have claimed other unions are watching what happens "like hawks". It is, they say, a dispute that now must be won at all costs.
But it's not going to be easy. The BMA too sees it as a point of principle - that an already over-stretched health service cannot be asked to do more without significantly more investment than it is getting and, of course, Saturdays should not be seen as part of the normal working week.
So both sides have dug their heels in. For some time it has been apparent that the tactic of ministers is to let the doctors strike and wait for them to run out of steam. They also know the end (or at least the beginning of the end) is in sight.
Contract offers are being made in May and come August the first tranche of doctors - about 6,500 out of 55,000 - will start on the new contract. More will quickly follow. Under the timetable for imposition, about three-quarters of juniors are likely to be on the contract within a year.
As that happens, it will become more and more difficult for the BMA to maintain its momentum. But that doesn't mean the dispute isn't damaging for government. The sight of thousands of junior doctors downing tools and walking out of intensive care, A&E and maternity units is one that will dog this administration for years to come.
Junior doctors also seem to be maintaining the public's support. Polling by Ipsos MORI for the BBC ahead of this week's walkout showed a majority - 57% - backed junior doctors. That is slightly lower than when the public were polled during the strikes where emergency cover was provided, but is higher than many expected. A majority also blame the government for the impasse.
The government had hoped public support would wane as the strikes went on. The fact that it hasn't is a worry for them.
But the BMA knows it cannot take the support for granted - and this is the crux of the problem facing the union.
Unlike strikes in other professions, its aim is not maximum disruption. The BMA worked with NHS England to ensure patients remained as safe as they could be. It has to - doctors have a professional duty to their patients.
Instead, the goal of the BMA is to apply pressure to the government (it is the same logic that underpins the judicial review which even those in the BMA acknowledge won't overturn the imposition).
It means it has to tread a fine line between causing disruption but not too much. It is why it did not strike during the night this week when it would have been much harder to get consultants to provide cover.
The union will now spend the coming days looking at how the strike went, before deciding its next steps. There is certainly talk of more strikes, but equally there is a recognition the delays to routine treatments are taking their toll. Some cancer patients also seem to have been affected.
This, in purely tactical terms, is the BMA's Achilles heel. They don't have a nuclear option - ministers know that. It's why the odds are stacked in the government's favour.