If you haven't noticed this is the week when Article 50 is triggered. The process that might result in the UK leaving the EU will begin. As many will know, for all the enormous faults in the EU I believe that this represents a significant error of judgement. That, though, seems to understate the real importance of what is about to happen.
Ignore all the reasons why I carefully included the word might in the second sentence: the lack of resources, vision, technical competence and maybe (when it all begins to go wrong) political will all suggest this process might not end with the UK leaving the EU. I do not think in that case that a foregone conclusion commences this week. And yet it's still true that everything changes.
The change is not the notice that will be given. Nor is it the fact that we could leave the EU. The change is that this is the end of a political economic era. After seventy years where integration and coordination has been the answer to most problems, the direction of travel has changed. Separation, differentiation and barriers are the supposed new order. And we haven't tried this before, at least not in living memory.
There is good reason for that. In that time we realised that rivalries had all too often ended in tears. And things much worse than tears.
What is more, we realised that whatever was said about competition, most good things seemed to come out of quite high degrees of cooperation.
On top of all that, we learned the very definite limits to dogma.
And now we seem to have forgotten all that. This week symbolises that collective amnesia.
So this could be the end of an era. But more accurately the only certainty is that it is the start of something new.
I say that because there are signs of hope. Trump's escapade in the same broad direction is already falling apart at the seams. The EU's intention to be transparent about its negotiating positions with the UK makes a mockery of the silly games British ministers seem intent on playing. And maybe, just maybe, sense might prevail for the reasons I have already noted.
Failure cannot be the basis for hope though. That's impossible. The hope is based on the fact that Article 50 intends to change everything, but the biggest change might be that simply trying this process will prove that there is a better direction of travel than separation offers. What the Article 50 process might prove is that if things aren't working (as many in Europe would agree) then we really do need to talk about constructive change, even if that is uncomfortable. In my optimistic moments I think Article 50 notice might create enough soul searching to lay the foundations for something new, way beyond the UK, and that some good might come of this after all.
So Article 50 notice ends an era. But what it does not guarantee is what the new one is. All we know is that it won't be the same as the one that is drawing to a close. For that most of us will be grateful.
That does not mean that we need not be almightily concerned about the process that starts this week. It just means that all that we can say for sure about it is that things won't be the same again. The revolution begins this week. We just don't know how many turns of the screw will be involved.