Most people, said La Rochefoucauld, would never fall in love if they’d never heard of it. Whether or not it is true of love, it might be true of mass shootings—that is, one mass shooting encourages another, so that they seem to come in clusters, piling horror on horror. Few people will believe that the mass shooting in Dayton, in which nine people so far have lost their lives, is entirely unconnected with the shooting just hours earlier in El Paso, in which 20 people have died.

The role of imitation in the commission of acts of violence by the susceptible has been known since at least the end of the eighteenth century, when romantic young men in Europe committed suicide after the publication of Goethe’s novel, The Sorrows of Young Werther, the eponymous hero of which killed himself for unrequited love. Even today, a suicide in a soap opera is sometimes followed by a brief spate of suicides—such that producers are now wary of depicting suicides, for fear of being accused of provoking them.

The violence of suicide, of course, affects principally the person who commits it, but often—especially among the young—it contains a significant element of aggression toward others, wreaking vengeance upon others for injuries done, real or imagined, to the suicidal person’s self-esteem. Mass shooting, which has been interpreted as a form of suicide because so high a proportion of perpetrators end up dead, takes vengeance to a higher level altogether. The suicide’s vengeance is directed against certain people in particular; the mass shooter’s is against people, or society, in general.

There are exceptions: the pilot who deliberately crashed a Germanwings airliner into the mountainside might have been trying to ruin his ex-girlfriend’s life forever by means of causing her an unassuageable sense of guilt; Anders Breivik killed those whom he believed would further dilute Norwegian national identity by their espousal of multiculturalism as a political ideology; and the El Paso shooter, yesterday, apparently explicitly intended to kill Hispanics. (The motives of the Dayton shooter are not yet known.) Some mass shooters have also returned to their former places of work and killed their former colleagues. More often, however, the victims and the grievance are only loosely connected—so loosely connected, in fact, that the mass killing suggests an inchoate rage against existence, against society, and against the perpetrator’s own life.

Modern mass killing, usually though not always by shooting, seems to have started (because imitation must start somewhere) with the case of Charles Whitman, who consulted a psychiatrist about his increasing bad temper and desire to shoot people—then killed his mother and father, climbed the tower on the campus of the University of Texas, and shot and killed 16 people at random and injured 44 others. This case has intrigued doctors ever since because at postmortem, Whitman was found to have a brain tumor, which might (or might not) have caused the removal of his normal inhibition against killing. In any case, he had undergone a character change before he killed.

Mass shooters tend to be of above-average intelligence but not high achievers. In a society in which fame, recognition, and success are of capital importance, in which lives of quiet desperation are not à la mode, they often feel deeply wounded, insulted in fact, by the supposed failure of society to take them at their own estimate, to recognize their true worth. They are rarely at ease in their personal relationships, either—but they look outward, not inward, for the source of their failures. The world for them is evil and unjust, and it will get, at their hands, what it deserves. In the process, of course, as another benefit, they will achieve their deserved fame or notoriety. They will be the subject of articles, news items, a Wikipedia entry, perhaps even of books; they will be an object of puzzlement by the learned and the famous. If they go far enough, they might even be mentioned by the president of the United States.

For the rest of us, the significance of these killings goes far beyond the statistical likelihood of our being the victim of such a crime, which remains minimal. It is that they reveal to us the dark potential of the human soul.

Photos: Mario Tama (L), Matthew Hatcher (R)/Getty Images