=A. Physical Characteristics.=--In the earlier period of childhood, from three to seven years, bodily growth is very rapid. Much of the vital force is thus consumed, and less energy is available for physical activity. The child has also less power of resistance and is thus susceptible to the diseases of childhood. His movements are for the same reason lacking in co-ordination. In the later period, from seven to twelve years, the bodily growth is less rapid, more energy is available for physical activity, and the co-ordination of muscles is greater. The brain has now reached its maximum size and weight, any further changes being due to the formation of associative pathways along nerve centres. This is, therefore, pre-eminently the habit-forming period. From the physical standpoint this means that those activities that are essentially habitual must have their genesis during the period between seven and twelve if they are to function perfectly in later life. The mastery of a musical instrument must be begun then if technique is ever to be perfect. If a foreign language is to be acquired, it should be begun in this period, or there will always be inaccuracies in pronunciation and articulation. =B. Mental Characteristics.=--The instinct of curiosity is very active in the earlier period of childhood, and this, combined with greater language power, leads to incessant questionings on the part of the child. He wants to know what, where, why, and how, in regard to everything that comes under his notice, and fortunate indeed is that child whose parent or teacher is sufficiently long-suffering to give satisfactory answers to his many and varied questions. To ignore the inquiries of the child, or to return impatient or grudging answers may inhibit the instinct and lead later to a lack of interest in the world about him. The imitative instinct is also still active and reveals itself particularly in the child's play, which in the main reflects the activities of those about him. He plays horse, policeman, school, Indian, in imitation of the occupations of others. Parents and teachers should depend largely upon this imitative tendency to secure desirable physical habits, such as erect and graceful carriage, cleanliness of person, orderly arrangement of personal belongings, neatness in dress, etc. The imagination is exceedingly active during childhood, fantastic and unregulated in the earlier period, under better control and direction in the later. It reveals itself in the love of hearing, reading, or inventing stories. The imitative play mentioned above is one phase of imaginative activity. The child's ideas of conduct, in this earlier stage of childhood, are derived from the pleasure or pain of their consequences. He has as yet little power of subordinating his lower impulses to an ideal end, and hence is not properly a moral being. Good conduct must, therefore, be secured principally through the exercise of arbitrary authority from without.