In one sense, it is reasonable to conclude that an hour of sleep before midnight is worth more than an hour thereafter. I am satisfied that there is greater exhaustion of the body from late than from normal hours, and it is difficult to get the full benefit from sleep when going to bed after midnight. At least the nerve strain of artificial light tends to produce a certain degree of vital depletion that one would not experience if his waking hours included only the daylight. Then again, there is probably some mysterious influence that we do not fully comprehend which makes sleep at night more restful than sleep during the daylight. Those who go to bed at midnight or thereafter use several hours of daylight in the early morning for sleeping. I realize that there are nocturnal animals and that the human race has developed nocturnal habits to a certain extent, but the human race and the animal life of the world generally have followed the habit through the ages of sleeping at night. Without doubt a revolutionary change in this habit has more or less effect upon the restful character of our sleep. Perhaps the mere question of light has much to do with it. Daylight is stimulating. Light has a chemical action and tends to stimulate animal metabolism. Darkness, or the lack of light, tends to a restful condition. Without doubt this question of light has much to do with the supposed benefits of sleep before midnight. The old saying that "early to bed and early to rise makes a man healthy, wealthy and wise" may not hold true in the matter of wisdom and wealth in all cases, but there is no doubt it has much to do with the development of health and vitality. CHAPTER XX: Mind-The Master-force for Health or Disease We hear of many miraculous achievements in the building of health and the cure of disease through mental influence. The mind is unquestionably a master-force. I will not go so far as to say it is limitless, for certainly a hungry man cannot imagine he is eating a dinner and secure the same benefits that he would from the meal itself. Nor can a man who is passing away into the other world, through a definite vital defect, bring back life through mental force. But we should remember that many diseases are to a great extent imaginary. And some of those not actually imaginary may at least be brought about through fears that are the results of abnormal delusions. And where such diseases are combated by mental forces of the right sort, a cure can be effected in many instances. In numerous cases, also, it is well to remember that the mental state is the actual cause of disease. You become blue, hopeless and to a certain extent helpless. You see nothing in the future. Life is dull. Ambition, enthusiasm, have all disappeared. It would not be at all difficult for this state of mind to bring about disease in some form.