Nelson Mandela was freed. I remember the report on the BBC vividly. Like the news from Eastern Europe just a few months previously, it seemed barely possible that it could happen. And that's the point, I suppose: that sometimes it seems impossible that something so entrenched and immoveable could change, right up to the moment that it finally becomes impossible for it not to change.

Eight years ago, I had the good fortune to be able to visit Robben Island, where Mandela and other political prisoners had been held for many years. I saw his prison cell, the quarry where he broke rocks, and the prison yard where he educated the young prisoners and planned for the future. Again, it was incredible that he should have retained such discipline and so even a temperament over so many years and after so much provocation and suffering.