My son, says she, what is the end of the attraction of mineral molecules towards each other?
SON. The production of a body having a determined form.
MOTHER. What is the end of the attraction of the plant for heat, light, air, the elements which it absorbs?
SON. The production of its own body, the development of its organs, and of its properties, its preservation.
MOTHER. And do you know, my daughter, what is the end of the attraction of the pistil and stamens of the flower.
DAUGHTER. The production of a being resembling its parents.
MOTHER. Why do we as well as the animals experience an inclination or attraction for certain kinds of food?
SON. It is evidently in order to incite to action the organs which procure to the organism the elements adapted to produce blood.
MOTHER. Why do both sexes of the same species experience an attraction towards each other?
DAUGHTER. For the production of young to perpetuate the species.