What we know of pre-birth training makes all this attempt made by a mother to influence the character of her unborn child by studying poetry, art, or mathematics during pregnancy seem totally impossible. How could such extremely complex influences pass from the mother to the child? There is no connection between their nervous systems. Even the blood vessels of mother and child do not join directly. An emotional shock to the mother will affect her child, because it changes the activity of her glands (腺) and the chemistry of her blood. Any chemical change in the mother’s blood will affect the child for better or worse. But we can not see how a looking for mathematics or poetic genius can be dissolved (溶解) in blood and produce a similar liking or genius in the child. In our discussion of instincts (本能) we saw that there was reason to believe that whatever we inherit (继承) must be of some very simple sort rather than any complicated or very definite kind of behavior. It is certain that no one inherits a knowledge of mathematics. It may be, however, that children inherit more or less of a rather general ability that we may call intelligence. If very intelligent children become deeply interested in mathematics, they will probably make a success of that study. As for musical ability., it may be that what is inherited is an especially sensitive ear, a special structure of the hands or the vocal (发声) organs connections between nerves and muscles. If these factors are all organized around music, the child may become a musician. The same factors, in other circumstance, might be organized about some other center of interest. The rich emotional equipment might find expression in poetry. The capable fingers might develop skill in surgery. It is not the knowledge of music that is inherited, then nor even the love of it, but a certain bodily structure that makes it comparatively easy to acquire musical knowledge and skill. Whether that ability shall be directed toward music or some other fields may be decided entirely by forces in the environment in which a child grows up.