A father, tired from his day of busy toil, may have a sick child, who for much of the night will not let him sleep. Such taxes as this, coming to one already run down and weak, cannot be braved frequently with impunity. Unless the five or six miles a day of Tom Brown and his fellow-Englishmen's "constitutional," or some equivalent, is resorted to, and the man kept well toned-up, one of these sudden calls may prove too severe, and do serious if not fatal injury. This toning-up is not all. If the bodily exercise is such as to get all the muscles strong, and keep them so, the very work that would otherwise overdo and exhaust now has no such effect, but is gone through with spirit and ease. There is that consciousness of strength which is equal to all such trifles. The very nervousness and worry which used to be so wearing, at the sudden and ceaseless calls of the day, have gone, and for the reason that strong nerves and strong muscles are very liable to go together, and not to mind these things. What does the athlete at the top of his condition know about nervousness? He is blithe as a lark all the day long. Dr. Mitchell says: "The man who lives an out-door life--who sleeps with the stars visible above him, who wins his bodily subsistence at first-hand from the earth and waters--is a being who defies rain and sun, has a strange sense of elastic strength, may drink if he likes, and may smoke all day long, and feel none the worse for it. Some such return to the earth for the means of life is what gives vigor and developing power to the colonists of an older race cast on a land like ours. A few generations of men living in such fashion store up a capital of vitality which accounts largely for the prodigal activity displayed by their descendants, and made possible only by the sturdy contest with nature which their ancestors have waged. That such a life is still led by multitudes of our countrymen is what alone serves to keep up our pristine force and energy." Now, while this extreme hardiness and tone cannot be had by a person who has twelve hours of busy brain-work daily in-doors, and only one of bodily exercise, still, much can be done, quite enough to calm and tranquillize, and to carry easily over those passes which used to be dreaded. If the man who habitually works too long without a rest would every hour or so turn lightly from his work, for even sixty seconds, to some vigorous exercise right in his office, or even in the next room or hall-way, until the blood got out of his brain a little, and the muscles tingled with a hearty glow, he would go back so refreshed as to quickly make up, both in the quantity and quality of his work, for the time lost. When his hour for exercise came, instead of having no heart for it, he would spring to it with alacrity, like the school-boy does to his play.