Many of us will have paused for a moment on Sunday to reflect on the tenth anniversary of 9/11.
There are very few days that can be said to have altered the direction of the world forever. 9/11 is one of those days. The poet W B Yeats wrote that after the Easter Risings of 1916 the world was "all changed, changed utterly" and this has been equally true of the last decade.
9/11 was one of those momentous events where we can all remember where we were when we first heard the news. It was the first world changing story to be captured on live rolling news - the first of many horrors that we could watch from home in real time.
Along with millions of others, I watched the second plane hitting the south tower of the World Trade Center, the absolute horror of office workers jumping to their deaths, and the collapse of both towers - images that will remain with us forever.
There were so many acts of heroism and inspiring courage that day. From the fire fighters who gave their own lives in trying to save as many as they could, to the passengers of American Airlines Flight 77 who overpowered the hijackers and brought their plane down in Pennsylvania.
Watching the commemoration in New York attended by President Bush and President Obama, it was impossible not to be moved by the words of those children who never knew their parents as a result of that day.
And listening to the roll call of the dead it was sobering to hear names from so many parts of the world. This was an international tragedy.
The political decisions that followed from that day have often divided us. But what surely unites us is a sense of solidarity with those who grieve still for their loss, in particular the 68 British men and women who were killed.
In her message to the memorial service in New York in 2001, The Queen said that "grief is the price we pay for love". 9/11 was perhaps the most significant political event of the last 50 years, along with the fall of the Berlin Wall. But it was also a very personal tragedy.