SUICIDE PLAYS HAVOC with any legal or moral system it touches. In law it is a kind of homicide. But it is the only kind where perpetrator and victim are the same, where the perpetrator therefore cannot be cross-examined or, if convicted, punished—except symbolically by punishing his relations or, in the imaginations of the living, by tortures no less extreme for escaping verification.

Ethics fares no better. Most moral rules are there to restrain egoism, in the interests of social harmony and general well-being. But suicide eliminates the “ego” altogether, so on that logic, it should be the most virtuous of imaginable acts. Indeed it can sometimes look like that, as in a war hero, or a self-sacrificer like Captain Oates, walking out into the snow when rations fell short on Scott's Antarctic expedition. But these acts are not suicide. Death must be the intention, not an incidental risk, to qualify as suicide. If Captain Oates had found a pork pie in the snow he would have eaten it or gone back to share it with the others. And whether an act with the doer's own death as the intention really does serve social harmony and general well-being has always the core of debate about it.

Historical assessments of suicide have tended to polarize. Either it has been deemed wicked beyond words, or it has produced pity and sympathy whilst not in itself (as distinct from any harmful consequences it may have, like leaving a family unprotected, or killing a dance-hall full of teenagers) condemned as heinous. Some medieval commentators treated suicide as the worst conceivable crime, worse than killing your own daughter or, in Judas, worse than his betrayal of Christ. At the other end of the scale, a play by the Roman philosopher Seneca has a character—probably ventriloquizing for the author—declare that to stop a person from committing suicide is worse than to kill him, because it robs him of the one freedom granted to all human beings at birth; the freedom, that is (in the image of another Roman philosopher), to “leave the room if it gets too smoky.”

This polarization is not just European. Early twentieth-century anthropologists tried to discover views on suicide among tribes far from European influence.