"What Black Feather? What do you mean?" said Marceline and Theophrastus with one voice. "Let's stroll back towards the Rond-Pont; and I'll tell you what I mean," said Adolphe. When they were under the trees, among the throng of careless strollers, Adolphe said: "You've heard of the water-finders?" "Of course," they said promptly. "Well, owing to some phenomenon, of which the explanation has not yet been discovered, these water-finders, equipped with forked hazel-twigs which they hold over the ground they are crossing, are able to _see_, through the different strata of the soil, the position of the spring sought, and the spot where the well must be sunk. I don't despair of getting Theophrastus to do for his treasures what the water-finders do for their springs. I shall take him to the place, and he will say, 'Here's where you dig for the treasures.'" "But all this does not explain what you mean by my Black Feather," interrupted Theophrastus. "I'm coming to it. I shall bring to this spot you, the treasure-seeker, as one brings the water-finder to the spot where one suspects the presence of water. I shall bring you there _when you have your Black Feather_." He paused, and then went on in his professorial tone: "I shall have to talk to you about Darwin; but you needn't be uneasy: I shan't have to talk about him for long. You'll understand at once. You know that Darwin devoted a great part of his life to some famous experiments of which the most famous were his experiments with pigeons. Desirous of accounting for the phenomena of heredity, he studied closely the breeding of pigeons. He chose pigeons because the generations of pigeons follow one another so closely that one can draw conclusions from them in a comparatively short space of time. At the end of a certain number, call it X, of generations he found once more the same pigeon. You understand, the same pigeon, with the same defects and the same qualities, the same shape, the same structure, and _the same black feather_ in the very place where the first pigeon had a black feather. Well, I, Adolphe Lecamus, maintain, and I will prove it to you, that to eyes opened by Darwin it is the same with souls as with bodies. At the end of a number X of generations, one finds the same soul, exactly as it was originally, with the same defects and the same qualities, _with the same black feather_. Do you understand?" "Not quite," said Theophrastus apologetically. "Yet I'm lowering myself to the level of your intelligence," said Adolphe, impatient but frank. "But it is necessary to distinguish between the soul which appears hereditarily and that which returns by reincarnation." "What do you mean?" said Theophrastus rather faintly. "An hereditary soul which revives the ancestor _has always its black feather_, owing to the fact that it is the result of a unique combination, since it exists in the sheath, the body, which is hereditary to the same extent. Is that clear?"