Sir Terry Pratchett is known to millions of young readers as the creator of a fantasy world where gods are self-obsessed, wizards cowardly, and heros hapless – the complete antidote to the neatly ordered world of Narnia. If there is a point to the chaos, other than humour, it is that no one is allowed to take themselves too seriously. Death, a parody of the grim reaper who appears in most of his Discworld novels, has a hard time understanding the living and being acknowledged by them. In the non-fictional world, Sir Terry is waging a parallel fight with our attitudes to legally assisted death. In his Dimbleby lecture, Shaking Hands With Death, broadcast last night, he called for the creation of euthanasia tribunals to give people with incurable diseases the right to medical help to end their lives. He even volunteered himself as a test case. Diagnosed two years ago with a rare form of early onset Alzheimer's, Sir Terry has faced up bravely to the disease he calls his "embuggerance". A patron of the Alzheimer's Research Trust, and a significant donor, Sir Terry has become a formidable champion of the rights of fellow sufferers, challenging Nice for the guidance it has issued over the drug Aricept. If sufferers from incurable diseases could chose the time of their death, then each remaining day of their life would be precious to them, he argues. Sir Terry enriches a complex debate with a unique brand of honesty, ­bravery and humour. For in the end, his death is no laughing matter.