Yesterday was one of the most remarkable and dramatic days in modern British history.
Yet it is not the only day in recent years that could have been described in that way, and it will not be the last.
That the government was found in contempt of Parliament over the refusal to publish the legal advice on the backstop is itself extraordinary, but also reflective of the shifting alliances in Westminster, that change by the day.
Most people who believe in democracy will seek maximum transparency that is consistent with good governance, but total transparency at all times would make it impossible to rule effectively, and would just give a further advantage to tyrannical nations that do not play by such rules, or indeed any at all.
All the main political parties accept the need for certain things to be private, as does the DUP, and as did Tony Blair when he regretted introducing the Freedom of Information Act. In any event, it is clear that it will be hard to get out of the backstop and almost impossible for Northern Ireland to do so. Yet if ever there was a need to know the exact legal position it is now, particularly when respected voices (including Martin Howe QC on these pages recently) are saying that London has made huge concessions that have far reaching constitutional implications, most of all for this Province — if we stay in the EU customs and regulatory zones and the rest of the UK leaves (as might be the long-term outcome).
While it is good to hear Graham Brady MP, the leading Tory backbencher, seek reassurance on the ability to escape the Northern Irish backstop before supporting the deal, it will be unacceptable if this merely results in some fresh joint communiqué from the UK and the EU. The latter does not accept reassurances, it demands legal certainty.
While the Withdrawal Agreement is now widely considered likely to fail, pundits are focusing on the margin by which it does so, to see if anything is salvageable. Thus it is important that that margin of defeat is a very large one indeed.