One should not despair of this view of child-life. Neither should one use it as an excuse for being bad, or for neglecting the training of children. On the contrary, taking the genetic view of childhood should give us certain advantages. It makes us see more clearly the _necessity_ of training. Every child must be trained, or he will remain very much a savage. In the absence of training, all children are much alike, and all alike bad from our present point of view. The chief differences in children in politeness and manners generally, in morals, in industry, etc., are due, in the main, to differences in training. It is a great help merely to know how difficult the task of training is, and that training there must be if we are to have a civilized child. We must take thought and plan for the education and training of our children. The task of education is in part one of changing human nature. This is no light task. It is one that requires, in the case of each child, some twenty years of hard, patient, persistent work. =Individual Development.= Heredity is a corollary of evolution. Individual development is intimately related to racial development. Indeed, racial development would be impossible without heredity in the individual. The individual must carry on and transmit what the race hands down to him. This will be evident when we explain what heredity means. By heredity we mean the likeness between parent and offspring. This likeness is a matter of form and structure as well as likeness of action or response. Animals and plants are like the parents in form and structure, and to a certain extent their responses are alike when the individuals are placed in the same situation. A robin is like the parent robins in size, shape, and color. It also hops like the parent birds, sings as they do, feeds as they do, builds a similar nest, etc. But the likeness in action is dependent upon likeness in structure. The young robin acts as does the old robin, because the nervous mechanism is the same, and therefore a similar stimulus brings about a similar response.