From Isaac Newton being hit on the head by an apple to the self-immolation of Tunisian street vendor Mohamed Bouazizi last year, history is littered with examples of seemingly insignificant events that have proven to be catalysts for much larger developments. The potential for a random alignment of events, small in number and short in duration, to irrevocably tip the balance of history, is immense.
The return of captured Israeli soldier Gilad Shalit one year ago yesterday was a momentous event in and of itself. But it had the potential to be much more significant. It had the potential to be a tipping point. At least, I thought it did.
Along with millions, I watched Gilad's return with teary eyes. I cheered the embrace between father and son, separated for so long. I watched approvingly as Israel's leader, Benjamin Netanyahu, reunited a family. I marvelled at the crowds lining the streets of Gilad's home town of Mitzpe Hila and smiled as President Peres paid his respects to a man 60 years his junior.
Some said the wrong decision had been made. Some called the agreement, which freed 1,027 Palestinian prisoners, a capitulation to terror. Others said it was disrespectful to the memories of those who had died at the hands of the murderers who were released to cheers in Gaza.
Without second guessing the thoughts of those who have lost loved ones to terror, or live with the constant threat of this, those fears do not appear to have manifested. Since October 18 2011, there has been no wave of kidnapping attempts, no string of new suicide attacks.
At the time, I argued that Israel had chosen the brave option, affirming the supreme value that Judaism places on life. Whatever he did in future, Gilad Shalit could rest assured that his release had strengthened the foundations on which the Jewish state had been built.
I stand by that, yet in the back of my mind I can't help but feel a twinge of disappointment. I played a small part in the campaign to keep Gilad's plight in the public eye, with Downing Street vigils and the "Faces for Gilad" scheme, which asked members of the public to take a photograph of themselves calling for his release.
Rightly or wrongly, Gilad became a symbol for campaigners and Israel advocates. Israel faces such constant struggles that in some ways supporters pinned our hopes on Gilad. Here was an area where we could make a tangible difference, ensuring that world leaders could not forget the teenager dragged through a tunnel into Gaza. Perhaps hope of seeing him freed became about more than merely bringing a man home. Perhaps, over the years, it became a symbolic act of redemption, a fillip for those who watched endless bad news from Israel and yearned for something positive to emerge.
I'm anything but a fan of "what if" history yet, what if? What could the release of Gilad have precipitated? An improbable, perhaps undesirable, détente between Israel and Hamas? A realisation that these two implacable enemies could, through a third party, find agreement? Perhaps even a change of direction for Hamas; a recognition that it had more to gain from engaging with Israel than from following an extremist agenda?
But, in the year since his release, little has changed. In fact, things appear to have deteriorated. There is the new threat of attacks across Israel's border with Sinai and ever-increasing instability on the northern border, as the fate of the Assad regime hangs in the balance. To the east, Iran draws ever closer to its nuclear goal. It's a depressing picture.
This week, we received the sad news that the body of Majdi Halabi, an Israeli solider missing for more than seven years, had been found in the Carmel. Other soldiers - including Zachary Baumel, Tzvi Feldman, Yehuda Katz, Ron Arad and Guy Hever - remain missing, some for nearly 40 years. Their families are in a limbo no one should have to endure. It is a reminder of how Gilad's story could have turned out differently.
Yet he returned to an Israel that is in a more precarious position than ever. For those who hoped that his homecoming might mark a turning point, our tremendous relief and joy at Gilad's return has been coloured by a sense of disappointment. Ultimately, Gilad is just one man, just one soldier, and Israel's hopes for a peaceful future will not rest on one man, one idea or one symbol being a catalyst for change.
But one year ago, a small part of me believed.
Jamie Slavin is public affairs manager of the Board of Deputies of British Jews