" Tarzan of the Apes was no sentimentalist. He knew nothing of the brotherhood of man. All things outside his own tribe were his deadly enemies, with the few exceptions of which Tantor, the elephant, was a marked example. And he realized all this without malice or hatred. To kill was the law of the wild world he knew. Few were his primitive pleasures, but the greatest of these was to hunt and kill, and so he accorded to others the right to cherish the same desires as he, even though he himself might be the object of their hunt. His strange life had left him neither morose nor bloodthirsty. That he joyed in killing, and that he killed with a joyous laugh upon his handsome lips betokened no innate cruelty. He killed for food most often, but, being a man, he sometimes killed for pleasure, a thing which no other animal does; for it has remained for man alone among all creatures to kill senselessly and wantonly for the mere pleasure of inflicting suffering and death. And when he killed for revenge, or in self-defense, he did that also without hysteria, for it was a very businesslike proceeding which admitted of no levity. "
― Edgar Rice Burroughs , Tarzan of the Apes (Tarzan, #1)