Traumatic for the nation; for police forces around the country; and above all for the innocent victims who have lost their homes, their livelihoods and even, in the most tragic cases, their lives.
The images of burning buses, looted shops and wrecked homes will not fade quickly. But our country must not - and will not - be defined by the actions of lawless rioters, opportunistic thieves and the members of violent gangs.
So now the work of rebuilding begins. Of the homes, shops and streets that have been damaged. In many places the work has been started by communities that have voluntarily and spontaneously come together to reclaim and clean up their neighbourhoods.
The best of Britain clearing up after the worst.
But there is also the slower, more painstaking, less visible rebuilding - the rebuilding of the affected communities themselves, and of people's lives. This is the work of years, not days.
Some long-standing social problems have been thrown into sharper relief: gang culture; failing families; a welfare system that traps too many in dependency.
The Government is already moving on all these fronts. Tougher action on knife crime; a radical welfare reform agenda; national citizens service; more investment in parenting; support for councils who want sanctions against those who wreck property. The last week gives these efforts even greater urgency.
So we will step up our efforts to deal with some of the long term problems at source. We will intervene more to deal with the hard core of the most problematic families, and we will, for the first time, provide early years education specifically targeted at two year-olds from the most disadvantaged families.
Intervening early saves a lot of heartache, crime and cost years down the line.
But right now the immediate need is to get to the bottom of what happened on our streets in the last week.
Nobody can credibly claim to know for sure, at this early stage, the precise reasons for the various acts of disorder, to have perfectly discerned the motives of the criminals on our streets.
We need to know who did what, and why they did it. We need to understand. I don't mean 'understand' in the sense of being understanding, or offering even the hint of an excuse. I mean understand what happened, to get as much evidence as we can. Then we can respond, ruthlessly but thoughtfully.
That is why we are commissioning independent research into the riots. Of course we don't need research to tell us that much of this was pure criminality, but the more we can learn the better.
Why did some areas and people explode and others not? What can we learn from those neighbourhoods and young people who remained peaceful? After all, it is worth remembering that the rioters were the exception, not the rule.
We need to know what kind of people the rioters were, and why they did it. That is also why we are looking into gang culture, so that we can combat it more effectively. In policy-making as in war, it is important to know your enemy.
Our policy response will be guided by our values of freedom, fairness and responsibility. It will also be based soundly on evidence, not anecdote or prejudice. Kneejerk reactions are not always wrong - but they usually are.
Overnight courts and instant justice are an essential part of the response. But while of course we have had to act swiftly and decisively, we have resisted the temptation to engage in overnight policy or instant announcements.
For me, what was most striking about the disorder was that so many of those involved clearly felt like they had nothing to lose.
Nothing to lose from destroying property and stealing goods, from getting a criminal record, from deeply damaging their future prospects for a job or education.
For many of the rioters, it was as if their own future had little value. It was about what they could get, here and now, and hang the consequences - above all the consequences for their victims, but even for themselves.
Clearly the people on the streets this week have felt little stake in society, and no responsibility towards their own communities.
Let me be clear. There is no excuse for this behaviour. None. As a liberal, I see violence and disorder of this kind as an attack on liberty, on the freedom for individuals to live and trade in peace in their own communities.
I think the best defence against this kind of nihilistic behaviour is to ensure that everyone has a stake in society, and everyone feels a sense of responsibility towards their own community. That, in turn, means giving people the opportunities to get ahead so they feel they have a stake in their own future.
That is why this Government has decided to focus our social policies on social mobility, because having opportunity - real opportunity - gives people the drive, discipline and responsibility to do the right thing.
Putting more money into schools with disadvantaged youngsters, expanding apprenticeships, increasing the provision of early years education. None of these will be quick fixes. There are no quick fixes. But these are the kind of investments that we need to make now, to spread opportunity in the future.
And I want to be clear about one important point. While I passionately believe that it is the responsibility of government and broader society to ensure that every individual has real opportunities, I am equally clear that it is the responsibility of the individual themselves to take those opportunities up, and to play by the rules.
What guides us should be the following conviction: people who play by the rules should be the ones who thrive. Those who think they can break the rules and reap rewards need to know that their time is up. This applies, above all, to those who broke not only the laws of the land, but also the rules of common decency, with their behaviour this week.
But there's a broader challenge here too. Too often, it looks as if people who break the rules can prosper. Tax evaders and benefit cheats; bankers who break the bank but feather their own nests; MPs who rob from the public purse.
At all times and in all parts of a society, we have to guard against the danger of a 'smash and grab' culture. A smash and grab culture in which, as the Chief Rabbi Jonathan Sacks put it yesterday, the only commandment is 'thou shalt not be found out''.
There is a danger that the only thing that stops people obeying rules is the fear that they might get caught.
In crime research there is a well-known theory dubbed the 'broken windows' effect, where one broken window leads to more and more crime.
I think there is a similar danger of a 'broken rule' effect, with people who see rules being broken in one walk of life then being more likely to break them in another. Rule-breaking spreads through society like a virus.
There was a lot of copycat rioting this week, as people acted out in one city what they saw happening in another. But there is a deeper copycat effect at work here too: people copying what they see as a 'take what you can, when you can' attitude to life, to society and to each other.
So while we can and will ensure that justice is done this month, and that the rioters and looters are properly punished, we must make sure it is done every month, everywhere.
The 'broken rule' effect means that we have to take a zero tolerance approach to all rule-breaking, all of the time. Rules are for all of us.
Politicians usually say at times like these, 'let's learn the lessons'. But they rarely do. This time it can be different. The burning shame we feel at the disorder on our streets has to be combined with a thoughtful determination to understand it, and an unbending commitment to stop it from ever happening again."
"Thanks to the Liberal Democrats the Government set the banks some extremely ambitious and challenging lending targets. It's clear from today's figures that banks have responded to pressure from Lib Dem Business Secretary Vince Cable to meet these targets.
"Labour left the UK with an overweight, unresponsive banking system which did not provide sufficient support for SMEs. Today's figures are encouraging, but it is still early days and we must not get complacent.
"Lending targets alone are not a silver bullet. Other key steps include reform of the banking system through the Vickers Commission, 250,000 additional apprenticeships and the Regional Growth Fund and enterprise zones.
"Together these will make our financial system more robust and provide essential support for small businesses."
"In her article on the detention of child refugees, Natasha Walter asks: "If a locked centre is called 'pre-departure accommodation', does it cease to be detention?" (Britain is still no refuge for refugees, 28 July). The current practices with regard to children awaiting deportation cannot be - and s hould not be - in any way compared to the shameful past.
"Children are no longer held for weeks, pending their removal from the country during and after their asylum or visa applications. Since current regulations were introduced, no child has been held under these circumstances. Only on the rare occasions when a family was denied entry at the border and there was no immediate return flight, have they been held in pre-departure accommodation until the next available flight, usually within 24 to 48 hours.
"The holding of any child is distressing because of the psychological harm it can cause: we're clear on that. But it would be inaccurate to compare this government's policies to the habitual long-term detention in inadequate facilities of the past. The coalition is not bringing "detention for families back into the asylum process", as Walter claims - it has gone out of its way to end it."
"Like everyone else - I watched the horror unfold on breaking news throughout the evening and night - as what started in Tottenham spread across our capital city and beyond.
"The bloody scenes of violence, peppered with raging fires, indicate that we have people in our communities who care nothing for the rule of law and order, nothing for human life and nothing for peoples' livelihoods. And there can be no justifications and nowhere to hide from such behaviour. We all need to stand together on this and condemn all those who perpetrated these acts. No ifs - no buts.
"David Cameron will chair an emergency meeting of Cobra this morning - and no doubt there will be following announcements on actions to be taken to restore law and order to our streets."
"Things are now becoming very serious in many areas of London including in my own borough of Southwark this evening.
"The Police must now have our support and they must be free to take the action they feel necessary to restore peace in our communities.
"In boroughs like Southwark, unless people have urgent reasons for being out on our streets, they should stay inside.
"I call on all parents, elders and other family members now to make sure that their teenagers and young adults stay inside and are not out on the streets
"And there is just one simple message for young people. Don't give in to the temptation to trash your own communities - these are the places which we all need for our future jobs, housing and prosperity."
"The IPCC must go about their investigation into the shooting of Mark Duggan as quickly as possible, and keep the family and community informed. To counter the problems of rumour and misinformation that may have helped trigger the unrest and may continue to do so, the council and police must continue to talk to community leaders and release as much information as they can. But we must all recognise a proper investigation takes time, and be patient to find out the full details of what happened in this shocking incident.
"Anyone who cares about Tottenham and its residents will be very upset to see such wanton destruction and violence in their community. It must have been a terrifying night for those living above shops and others accidentally caught up in the mayhem.
"There is no possible justification for violence, arson and looting. Tottenham has a great many problems and challenges, none of which will be helped by these actions."
"The looting and destruction will leave a scar on this area for many years, and risks setting back Tottenham's regeneration decades. The vast majority of Tottenham residents will rightly be very angry about the
damage done to the community they love.
"The police and authorities must do all they can to bring those guilty of such terrifying violence and destruction to justice. The Council needs to do all it can to help Tottenham's shops and businesses recover from this terrible damage."
"On behalf of the residents of Haringey, I would like to thank all the fire fighters and police officers who worked so hard to try to keep people safe, and express our sympathy to those officers who have been injured."
The government Advocate for Access to Education Simon Hughes published his final report to the Prime Minister and Deputy Prime Minister last week. The report makes over 30 recommendations to increase participation in higher education. These are directed towards schools, colleges, universities, government and regulators.
Simon believes that efforts to increase participation in universities from underrepresented groups should start as early as 10 and 11 and better careers information, advice and guidance is vital. He also recommends that the national scholarship scheme should offer scholarships to every school and college.
Simon has written this report after spending six months listening to the views of young people, teachers and parents from around the country as well as education professionals and representatives from charities, universities, trade unions, and other representative organisations.
"Parents are the most important influence in a child's early life. The experiences of children in their earliest years, good or bad, can shape the rest of their life.
"An overwhelming amount of research has stressed the importance of the first few years in a child's development and the effect these foundation years have on their chances later in life.
"Ensuring that parenting has the status and support it deserves is a key part in supporting a child's development and the Liberal Democrats will be working with the Liberal Democrat Children's Minister, Sarah Teather, to put this into practice."
"Ofcom should be praised for consigning Labour's site blocking laws to the bin.
"Site blocking may sometimes be necessary, but that doesn't excuse the Digital Economy Act's sorry attempt to enable it.
"Internet providers and rights-holders must now devise a simple solution. Those offending on a massive scale should be stopped without threatening every website under the sun."
"The PCC has clearly failed. It was limited in its powers and its ambition. What we need now is a bold regulator that editors can't ignore.
"Several people involved in the phone-hacking scandal have already paid for their mistakes, with one notable exception. James Murdoch should now be considering his position.
"Peta Buscombe joins a list that should grow longer yet."
