All our feeling that human nature has degenerated in physical constitution has been completely contradicted by the reaction of our young soldiers to camp and trench life. They have gone back to the lack of comforts and conveniences of the pioneer days and have had to submit to the outdoor life and the {132} hardships that their pioneer grandfathers went through and have not failed under them. The boys have come out of it all demonstrating not only that their courage was capable of supporting them, but with their physical being bettered by the conditions and their power to stand suffering revealed in a way that would scarcely have been believed possible beforehand. {133} CHAPTER IX THE WILL AND AIR AND EXERCISE "And wishes fall out as they are willed." _Pericles_ Very probably the most important function of the will in its relation to health is that which concerns its power to control the habits of mankind as regards air and exercise. It is surprising to what an extent people neglect both of these essentials of healthy living in the midst of our modern sophisticated life, unless the will power is consciously used for the purpose of forming and then maintaining habits with regard to these requisites for health. It is a very fortunate thing that instinct urges the child, particularly the infant, to almost constant movement during its waking hours. Children that are healthy and that are growing rapidly, boys somewhat more than girls, are so constantly in movement that one would almost think that they must be on springs. Whenever they discover that they can make a {134} new movement, they proceed to make it over and over again until they can do it with facility. There is no lolling around for them; as soon as they wake, they want to be up and doing, no matter what the habits of the household may be. They are constantly on the move. We know that this is absolutely essential for growth as well as for the proper training of their muscles, but it is a very fortunate thing that children do it for themselves, for if their mothers were compelled to train them, the task would be indeed difficult. All mother has to do is to control them to some extent and keep them from venturing too far, lest they should hurt themselves.