This practice, like all those which resolve themselves into absorption, is assuredly dictated by experience. Neither a man nor an animal can, in principle, become addicted to an act which is harmful to him. Between acts that are harmful, and acts that are salutary, there is a whole series of games, but it is difficult to admit that a daily game is a harmful act. Why do not peasants eat certain abundant rodents? It is easy to answer by offering taste and disgust as pretexts; but this is reversing the logical order of the terms of the argument. A food does not disgust by its odour. The odour of a food disgusts because this food is harmful or useless. To understand this, without the necessity of insisting upon it, it is enough to think of all those foods with nauseous odours, which we appreciate much more than those which might be considered pleasant. Such is the fruit of experience, that is to say, of knowledge. I believe that absorption should be considered one of the best means we have of appreciating the practical value of certain parts of the external world. Agriculture, kitchen-gardening, cooking, pharmacy almost entirely, are born of it. Assuredly men, even the rarest chemists and physiologists, could suck a kola-nut for years, without suspecting those virtues that savages found quite simply by cracking it with their teeth. They jest who, ignoring not only the importance but the very existence of this sixth or seventh or tenth sense, attribute to taste or to smell a mysterious power of divining the harmfulness of a plant or of its fruit. How can they help seeing immediately that this preservative instinct, if it be hereditary, has had a beginning, and that, at this beginning, there was a fact of knowledge? The traditional notion of instinct must be left in the old theological and spiritualistic repertories. It serves simple people as an easy means of distinguishing man from the animals. Animals have instinct, man has intelligence. There are proofs. Man poisons himself with mushrooms, frugivorous animals never. What man? Not the traditional peasant surely. Only the _déraciné_ or the city-dweller, who has naturally lost an instinct which was useless to him. This proof proves only that it is dangerous for man, as for the other animals, or for plaints themselves, to change their habitat. There is a painful, uncertain transitory phase. It is during this phase that we go into the woods, picknicking, and gather toadstools. But rabbits in cages, when given wet grass or vegetables instinctively unknown to them, allow themselves to be completely poisoned. Free, it would never have occurred to them to crop at dewfall, because their ancestors, dwelling in extremely thick woodlands, were ignorant of the very existence of the dew, and transmitted distrust of wet grass to their offspring.