Recently, Martin Amis noted, half-jokingly, that becoming a grandfather was like receiving a telegram from the mortuary. If so, then the news last week that his closest friend, Christopher Hitchens, has cancer of the oesophagus is more like getting a generational summons from the grave. That is not to overstate the seriousness of Hitchens's diagnosis – although oesophageal cancer is indeed a grim condition – but simply to recognise the legend of an indestructible constitution that has long attended the celebrated journalist, polemicist, author, anti-theist and bon vivant. And no less to acknowledge the vitality habitually displayed by Hitchens in...