THE first jump from the high board is the hardest. It’s a long, slow way up and a long, quick way down. You step off and there’s nothing underfoot. You step off and suddenly the world is unrecognisable. You don’t know whether this will end badly or well.

Next time up: not so hard. Next time, if you’ve quelled your fears, you can see why so many others have made this jump. Each one of them would do it again. The board wasn’t so high. The unknown becomes known the minute you take a step forward.

The short year since the end of Scotland’s long referendum has been busy. There has been the small matter of a political world turned upside down. The statistics – votes, affiliations, opinion polls – have been remarkable. They have been doubly significant because they have come like derisive retorts in the aftermath of a defeat.

If we could live off theories to explain it, we wouldn’t go hungry. The historical decline of Labour in Scotland, or of all the old European centre-left parties; the rise of “populism”, or the rise of nationalism; the outrage against austerity and pillage; a universal disgust with establishments, elites and tales told to frighten children: all of that and more is offered.

For our part, we know one thing above all. It’s the fact that demands the theories: Scotland has changed utterly in a year. The country has altered. The way it looks at itself is different. We know how to jump.

You wouldn’t think so, necessarily, while immersed in daily life. There is no real case for claiming that, all of a sudden, the country exudes confidence and positive thinking. There are, as ever, plenty of what politicians like to call “challenges”. What’s changed is a habit of mind that has been with us for generations: precious few believe things will stay as they are. In Scotland, that’s new.

The ripples from the last splash are spreading still. When the chance comes again, something other than Better Together will have to be mounted by those who say the board is too high, or the water too deep (“And besides we cannae swim”). We know now what happens when you decide to make the jump: some people tell you fearsome lies about the fate that awaits. And we know what doesn’t happen: the world doesn’t come to an end.

Those of us who tried the jump last September live with the knowledge. Decades of doubt and fear were dissolved with a choice while deceitful voices tainted their cause with hysteria. The thing they had called impossible turned out to be perfectly possible, perfectly conceivable, perfectly normal. In some ways, self-determination turned out to be no big deal.

It makes a second attempt inevitable. Consciousness of that truth, more than anything, has been the change. Two recent polls have said that this time Yes would win: it does no harm to believe it if you remember that polls come and go, that tides rise and fall. More interesting are the surveys purporting to show what people think will happen.

Yes or No, they go with the grain of perceived reality. If asked, people say that one way or another, for good or ill, Scotland will again be an independent country. That is, for a considerable majority, just a fact of life now.

It’s a new fact, but omnipresent. It is the heart of political argument. When will there be another referendum? Can – would – Westminster attempt to prevent it? Why is the SNP’s leadership “making no plans”? The details of the debate are less important than the debate itself. But even – especially – Unionists know the game is up. They know all about those elections and those polls. They don’t believe they can win a second time.

We know how the thing is done. We have kicked “the issues” to death. Those who want independence are busy repairing the flaws in the last campaign’s case, whether the flaws involve the currency, the economy, or international relations. Above all, there is a psychological and emotional readiness. We’ve been to the high board. Unionists, staring aghast at the lovely water, have been there with us.

In other places, at other times, Scotland’s independence would already be an established reality. That truth does not elude the guardians of the British state. If only electoral politics was at stake negotiators would be quibbling over the divvying of the national debt. If former definitions of “mandate” still applied, the Scottish National Party would be home and dry. It completed that part of the jigsaw in May’s general election. Its ability to do so was a consequence, stunning and direct, of last year’s referendum.

You can argue over whether “just” 50% of the vote entitles a party to anything. Do so and you will display a certain desperation. The Nationalist party was liberated, finally, from the hesitations born of our old allegiances, ancient doubts, and well-cultivated fears. Until this May, remember, there was supposed to be “no point” in sending SNP MPs to Westminster. One moment on the high board and we were beyond that.

Those of us who were ready to jump last year have been joined by others. That was neither suspected nor predicted. In the hours and days after September 18, there was a confident Unionist expectation that the appetite for independence would fade, that Yes voters would “move on”. Instead, say those polls, many of those who decided against independence have changed their minds.

Some, on either side, have a slightly quirky view of all this. We hold that Scotland is already as good as independent, at least in its own mind. It is as though another referendum is just a detail to be attended to when the moment is most convenient. The case of Nicola Sturgeon is relevant. She “speaks for Scotland”, they say. If so, seven in 10 Scots admire her, sometimes hugely, for that.

Such is politics, but not to be dismissed. Politics provides yardsticks that are as good as any for measuring what has gone since last September. The SNP’s dominance is now just an accepted reality. It is not, moreover, a reality that anyone expects to see alter any time soon. Then there are the consequences: if Westminster votes for Trident renewal, an escalation in Syria, or withdrawal from Europe the row will echo around these islands. There is no longer such a thing as business as usual.

At the back of it all stands the prospect of that second referendum. Unionist unease is palpable. There is a belief that “the Scots” can push the button whenever they choose and conclude business left unfinished last September. This is simplistic, but essentially true. It is true because, in the year since 55.3% of voters said No, it has become a commonplace belief among Scots. Given David Cameron’s government, no-one expects the appetite to diminish in the years ahead.

Up on the high board, you have a whole new perspective. You concentrate on what you mean to do. Afterwards, the victory is in realising that it wasn’t so difficult after all. It wasn’t difficult at all.