Mobilizing an effective international response to the scourge of crimes against humanity is, for those of us in the world of policy and ideas who spend a lot of our time trying to do just that, nearly always a matter of more than just abstract, intellectual commitment. I have found that for the great majority of us that commitment has welled up from some personal experience that has touched us, individually, very deeply. For many that will be bound to be scarifying family memories of the Holocaust; for others the experience of personal loss or closely knowing survivors from Rwanda or Srebrenica or any of the other mass atrocity scenes of more recent decades; for others still, perhaps, the awful sense that they could have done more, in their past official lives, to generate the kind of international response that these situations required.

For me it was my visit to Cambodia in the late 1960s. I was a young Australian making my first trip to Europe, to take up a scholarship at Oxford. Inexhaustibly hungry for experience, like so many of my compatriots before and since, I spent six months wending my way by plane and overland through a dozen countries in Asia, and a few more in Africa and the Middle East as well. In every one of them, I spent many hours and days on student campuses and in student hangouts, and in hard-class cross-country trains and ramshackle rural buses, getting to know in the process – usually fleetingly but quite often enduringly, in friendships that have lasted to this day – scores of some of the liveliest and brightest people of their generation.