In all this talk of early elections, of dates and delays, there is one common if, for some, uncomfortable premise. It is the constant factor in the calculus run by all the political parties and by the warring factions within them. Put simply, it is the fact that vast swathes of the electorate are unprecedentedly hostile to the idea of making Jeremy Corbyn their prime minister.

MPs have voted for the bill to go forward, but that doesn’t mean they all back it – or that the saga is ending any time soon

It would be tempting to call this the moment of truth, had truth not been an early casualty of a Brexit saga that was mired in lies and deception from the very start. Even so the Brexit story, which has twisted and tormented this country for the last three and a half years, is at a moment of decision. Outside parliament, hundreds of thousands will gather to make one, possibly last, plea to stay in the European Union. Inside, MPs are due to vote on an agreement that, if it passes, will see us make the break in less than a fortnight – thereby ending British participation in a dream that has animated Europe ever since the final bombs fell in 1945.

Donald Trump is set to face impeachment for a phone call that came to light last month. The crimes he committed in that call were serious and merit the ultimate sanction that can be imposed on a sitting president, namely removal from office. And yet even since that conversation took place, in fact this very week, Trump has had another call that included an act that might not meet the constitutional standard of “high crimes and misdemeanours” and for which he will face no such punishment – but whose consequences will surely be even graver. For they will be measured in life and death.

It is one of the stranger aspects of the Brexit debate. When the plea is raised to remember the Good Friday agreement, to do nothing that might jeopardise the fragile peace that has held in Northern Ireland for two decades, that plea usually comes in a continental European accent. Of course, Irish politicians have been saying it loudly from the start, but this week it was striking to hear French, German, Dutch or Belgian voices explaining to British TV and radio audiences why the EU couldn’t possibly accept Boris Johnson’s revised Brexit plan because of the risk it posed to peace in a corner of the United Kingdom where a bloody conflict had raged within recent memory.

Since 2016, Britain and the United States have grappled with a shared fate, facing down the conjoined twins of populism: Brexit and Trump. This week, at long last, came the first signs of a reckoning. After three years in which the winners of 2016 have mocked, pushed or trampled on the constitutional constraints that sustain a liberal democracy, the constitutions – on both sides of the Atlantic – struck back.

The sensation has become so rare, it took a moment to realise what it was. But following Wednesday’s ruling by Scotland’s highest civil court that Boris Johnson’s suspension of parliament was unlawful, the feeling was unmistakable. It was optimism. Admittedly, it was optimism in its weakest form: not the confident certainty that all would turn out for the best, but rather a fragile flicker of hope that things might not be so bad after all.

When answers are in short supply, sometimes the best we can do is try to ask the right questions. Some of those dive into legal and constitutional arcana, as experts try to work out how Boris Johnson can climb out of the hole he has spent this last week digging ever deeper for himself. Now that the opposition parties have refused to accede to his cunning plan for an October election, and will next week see passed into law their demand that he seek an extension of Britain’s EU membership, he’s left with a series of unpalatable alternatives – from breaking the law to resignation to tabling a motion of no confidence in himself.

When some of the best-known Conservative figures of the last half-century are booted out of their party, when a new prime minister loses his first parliamentary vote and his governing majority on the same day, when historians are referring to this as a “revolutionary moment”, you know something of great significance is going on. But what exactly is it?