Lettre sur les aveugles [Letter on the Blind] (1749)
Contexto: As to all the outward signs that awaken within us feelings of sympathy and compassion, the blind are only affected by crying; I suspect them in general of lacking humanity. What difference is there for a blind man, between a man who is urinating, and man who, without crying out, is bleeding? And we ourselves, do we not cease to commiserate, when the distance or the smallness of the objects in question produce the same effect on us as the lack of sight produces in the blind man? All our virtues depend on the faculty of the senses, and on the degree to which external things affect us. Thus I do not doubt that, except for the fear of punishment, many people would not feel any remorse for killing a man from a distance at which he appeared no larger than a swallow. No more, at any rate, than they would for slaughtering a cow up close. If we feel compassion for a horse that suffers, but if we squash an ant without any scruple, isn’t the same principle at work?