Leg exercise has perhaps a higher value than that of any other part. Man is by definition an upright being, but only after a long apprenticeship.[16] Thus the hand was freed from the necessity of locomotion and made the servant of the mind. Locomotion overcomes the tendency to sedentary habits in modern schools and life, and helps the mind to helpful action, so that a peripatetic philosophy is more normal than that of the easy chair and the study lamp. Hill-climbing is unexcelled as a stimulus at once of heart, lungs, and blood. If Hippocrates is right, inspiration is possible only on a mountain-top. Walking, running, dancing, skating, coasting are also alterative and regulative of sex, and there is a deep and close though not yet fully explained reciprocity between the two. Arm work is relatively too prominent a feature in gymnasia. Those who lead excessively sedentary lives are prone to be turbulent and extreme in both passion and opinion, as witness the oft-adduced revolutionary disposition of cobblers. The play problem is now fairly open and is vast in its relation to many other things. Roof playgrounds, recreation piers, schoolyards and even school-buildings, open before and after school hours; excursions and outings of many kinds and with many purposes, which seem to distinctly augment growth; occupation during the long vacation when, beginning with spring, most juvenile crime is committed; theatricals, which according to some police testimony lessen the number of juvenile delinquents; boys' clubs with more or less self-government of the George Junior Republic and other types, treated in another chapter; nature-study; the distinctly different needs and propensities of both good and evil in different nationalities; the advantages of playground fences and exclusion, their disciplinary worth, and their value as resting places; the liability that "the boy without a playground will become the father without a job"; the relation of play and its slow transition to manual and industrial education at the savage age when a boy abhors all regular occupation; the necessity of exciting interest, not by what is done for boys, but by what they do; the adjustment of play to sex; the determination of the proper average age of maximal zest in and good from sandbox, ring-toss, bean-bag, shuffle-board, peg top, charity, funeral play, prisoner's base, hill-dill; the value and right use of apparatus, and of rabbits, pigeons, bees, and a small menagerie in the playground; tan-bark, clay, the proper alternation of excessive freedom, that often turns boys stale through the summer, with regulated activities; the disciplined "work of play" and sedentary games; the value of the washboard rubbing and of the hand and knee exercise of scrubbing, which a late writer would restore for all girls with clever and Greek-named play apparatus; as well as digging, shoveling, tamping, pick-chopping, and hod-carrying exercises