Hindsight is a wonderful thing. So when something hitherto unforeseen happens, there are always those who claim they foresaw it. I am not one of them. Although I was the first MP publicly to nominate Jeremy Corbyn as leader I did not predict the subsequent events. Nor did the bookies. They had him as a 100:1 outsider.
Equally remarkable as the election of the new leader was the movement of at first hundreds, then thousands, and eventually tens of thousands of people coming to public meetings to discuss politics. Then they moved into that venerable political institution: Labour Party. The commonly held view had been that ideology, politics, and political parties were all perishing away. This consensus was shaken to its foundations, as was the rest of the political landscape when this new spontaneous movement emerged.
Three streams of thought - separate, but linked together by the idea that it 'doesn't always have to be like this' - emerged. These three are the mandate which will shape Jeremy's leadership. Within each stream there is much to be debated and there will clearly be shades of view about the detail. But the broad outlines are clear.
In the first place, during the Corbyn4Leader rallies there was a hunger for a new look at Britain's place in the world. And this is not simply because of the mistakes at the time of the Iraq war.
We are a trading nation, a leading economy, we sit on the Security Council. Britain continues to play a major role in the world. But on the other hand we need not be slavish to the old imperial ways. In future Labour should be a voice for engagement with those who share our values supporting the authority of international law and international institutions, not acting against them.
With world events unfolding rapidly new challenges are emerging which requires careful thought and even more careful action. Climate change and deep poverty, terrorism and localised conflicts, some with global potential, the rise of China and the BRIC countries, the terrible suffering of refugees fleeing war-torn countries, the threat of ISIS and the tensions within the European Union all these are quite recent developments to which we must respond in new ways.
If the United States can do deals with Iran and Cuba ( impossible to imagine a few years ago) what new directions might Britain take whilst maintaining its old alliances to both foster the long term interests of its people and to be a force for progress and peace in the world?
Secondly, the way our economy works needs to be transformed. Many of the precepts by which our economic life is governed were challenged over the summer. For example, the notion that wealth is exclusively produced by billionaires who therefore deserve exceptional income and taxation arrangements. Or the notion that cutting budgets of precious public services is the only way to tackle the deficit.
The economy isn't working for most working people. The explosive expansion of inequality was the central argument which drove the hunger for economic change of so many people who attended the rallies. Now many professional economists are also rejecting the orthodoxy of recent decades.
Our economy is dangerously unbalanced and needs to be rebuilt. It is out of kilter as a result of the overwhelming dominance of the City of London, of retailing and the service sector. Asset and house price bubbles are no strong foundation for stable growth. And there is no equilibrium in regional terms. Large areas of our country have been left behind following the rapid deindustrialisation which took place in the last few decades.
Thirdly, many people feel that the depth of the economic problems facing the country is the responsibility of a political system which has failed. Jeremy Corbyn has reiterated the urgent need to reform our political culture and our constitution. His plain speaking and avoidance of the usual weasel words made a refreshing start.
But we are determined to give the whole nation the chance to take part in a conversation about what sort of devolution and governance we need. Political reform is not just about changing our institutions like the House of Lords (important though that is) it is about creating a more participative and bottom up political culture.
Power and authority can no longer reside exclusively in the hands of closed elite circle in Whitehall. Particularly so when so many of our fellow citizens have come to the conclusion that this closed circle has too often exercised power in its own interests rather than those of the country as a whole.
Learning from the events of the summer we can begin to renew both our party and eventually the country as a whole.
In effect, what happened over the summer is that a new movement emerged. Restless with an unsatisfactory status quo which no longer serves Britain, people in their tens of thousands turned to Labour as their political party of choice. It is the task of the whole party to welcome our new colleagues, to listen, learn and perhaps adapt our party's culture and practices to these exciting new challenges.
Adapting Marshall McLuhan's original phrase, it is now clear that the primary lesson of the last few months is that it is 'the movement which is the message'. It's a movement that has already changed the Labour party that can now go on and change the country for the better.
Jon Trickett is the Labour MP for Hemsworth, the shadow communities secretary and shadow minister for constitutional convention