Air and light are so intimately connected with each other that it is as well to speak a few words [Pg 24] here on the value of light. Light is as indispensable to life as air itself. Hence it is that Hell is represented as completely dark. Where light cannot penetrate, the air can never be pure. If we enter a dark cellar, we can distinctly perceive the smell of the foul air. The fact that we cannot see in the dark shows that God has intended us to live and move in the light. And Nature has given us just as much darkness as we require in the night. Yet, many people are in the habit of sitting or sleeping in underground cellars, devoid of air and light, even in the hottest summer! Those who thus deprive themselves of air and light are always weak and haggard. Now-a-days, there are many doctors in Europe who cure their patients by means of air-bath and sun-bath alone. Thousands of diseased persons have been cured by mere exposure to the air and to the sunlight. We should keep all doors and windows in our houses always open, in order to allow the free entrance of air and light. Some readers may ask why, if air and light are so indispensable, those who live and work in cellars are not visibly affected. Those who have thought well over the matter would never put this question. Our aim should be to attain the maximum of health by all legitimate means; we should not be content merely to live anyhow. It has been [Pg 25] indubitably established that insufficient air and light give rise to disease. Dwellers in towns are, as a rule, more delicate than those in the country, for they get less air and light than the latter. Air and light, then, are absolutely indispensable to health, and every one should remember all that we have said on the matter, and act up to it to the best of his ability. Chapter IV WATER As has been already pointed out, air is the most indispensable to our subsistence, while water comes next in order. Man cannot live for more than a few minutes without air, but he can live for a few days without water. And in the absence of other food, he can subsist on water alone for many days. There is more than 70% of water in the composition of our food-stuffs, as in that of the human body. Even though water is so indispensable, we take hardly any pains to keep it pure. Epidemics are as much the outcome of our indifference to the quality of the water we drink, as of the air we breathe. The drinking of dirty water very often produces also the disease of the stone.