As the news was breaking that murder and terror had returned to Westminster the instinctive focus of many was to ask, "who did this?".
Before last June, that would have been my first thought too.
But since the murder of my wife, when something like this happens nowadays my first thoughts are with those caught up in the violence and with their loved ones. The partners and family members first desperate for news and then forced to confront the unthinkable. The realisation that the person they were expecting home wasn't going to be there. The numbing shock and then the excruciating judgements about how to tell others, especially when children are involved.
And we have to remember that for every person directly affected by the carnage, whether they lost their lives or were injured, there are dozens more whose expectations of today, of next week, of the foreseeable future have been shattered.
They will be numb and in varying degrees of disbelief and shock. If my experience is any guide, they will also be heartened to see Britain coming together once again, in quiet determination not to be cowed.
I saw that spirit as I cycled through the streets of London yesterday. It is a resilience born of simple common sense and it convinces me that the terrorists failed again on Wednesday and always will.
Alongside those thoughts, I try to focus not on the individual act of hatred and cowardice, but on the hundreds of acts of kindness, bravery and love that followed in response. The selfless bravery of PC Keith Palmer. The people who went to help others on the bridge, the fire crew who rescued the injured woman from the Thames. Tobias Elwood who gave mouth to mouth. And many more who we will never know but who did what they knew was right.
It is those people who represent our country, not the extremists.
Of course, there are some who choose to respond to extremism with extremism. They share the belief that motivated the terrorists - that different people shouldn't mix - and they see this as an opportunity to try to sow division within our communities.
They are doing the work of the terrorists for them.
What I know is that the man who did this is no more representative of British Muslims than the man who killed Jo was representative of white men from Yorkshire. Both were extremists, both were terrorists and both should be judged for what they did, not what religion they professed.
So the answer to the question "who did this?" didn't affect me greatly. By contrast, I was conscious that there were Muslims who did things of real significance on Wednesday. People who are worthy of our immense gratitude. Not because they are Muslims, but because they are women and men who like most of us know without thinking what needs to be done and get on with it.
The police officers who while telling others to move to a place of safety went in to secure a crime scene where the possibility of further violence was a real possibility. The nurses and doctors and orderlies whose professionalism is what defines them, not their religion. The teachers who had to explain to our children that something terrible had happened but that they shouldn't be afraid.
It doesn't take an act of terrorism to make heroes of these people. They are heroes every day of their lives in my opinion, whether Muslim or Christian, Jew or Hindu, atheist or agnostic. We can't all be like them. But we can support them and do a little bit, wherever we are and whatever our role in life, to drive the haters and the extremists even further from our hearts than they are already.
When we come together as communities the terrorists fail. When we open our arms to each other they despair. They want to take us from unease to suspicion to fear and then to hatred. Our way, the British way, is from dismay to resilience to inclusiveness and then to affirmation of everything we have in common.
When Jo was killed I sensed that happening around me before I had the time or the ability to analyse what was going on. If a little of that can help sustain those who are suffering today it will make their healing process easier to bear and further strengthen our communities against the extremists and their futile destructiveness.