Undoubtedly the most important factor for the preservation of health is an abundance of fresh air. At certain seasons of the year this is not only easy and agreeable, but to do anything else imposes hardship. In our climate, however, there are about six months of the year in which it requires some exercise of will power to secure as much open air life as is required for health. There are weeks when it is too hot, there are many weeks when it is too cold. The cold air particularly is important, because it produces a stimulating vital reaction than which nothing is more precious for health. We have no tonic among all the drugs of the pharmacopeia that is equal to the effect of a brisk walk in the bracing air of a dry cold day. After a long morning and {137} perhaps a whole day in the house, even half an hour outdoors will enable us to throw off the sluggishness consequent upon confinement to the indoor air and the lack of appetite and the general feeling of physical lassitude which has followed living in an absolutely equable temperature for twenty-four hours. Sometimes it requires no little effort of the will to secure this, and to continue it day after day without missing it or letting it be crowded out by claims that are partly real and partly excuses, because we do not care to make the special effort required. What humanity needs is regular exercise in the open air every day. As it is, between the trolley car and the automobile, very few people get what they need. Any one who has to go a mile takes a car or some other conveyance and between waiting for the car and certain inevitable delays it will probably take ten minutes or more to go the mile. In five minutes more one could walk that distance and secure precious exercise besides such diversion of mind as inevitably comes from walking on busy city streets and which makes an excellent recreation in the midst of one's work. For it is quite impossible in our day to walk along city streets absorbed in abstract mental {138} occupations. One of the objections to walking is that after a while it can be accomplished as a matter of routine without necessarily taking one's mind away from subjects in which it has been absorbed. It is quite impossible for this to happen, however, on modern city streets. "The outside of a horse", it used to be said, "is good for the inside of a man." The main reason for this was because it is impossible for a man to ride horseback, unless his mount is a veritable old Dobbin, without paying strict attention to the animal. The same thing is true as regards city pedestrianism, especially since the coming of the auto has made it necessary to watch our steps and look where we go.