Accounts received from persons who have been shipwrecked, or exposed in open boats upon the water in situations of great personal danger, and where, in consequence, no sleep could be indulged, go to confirm this view; and, though these accounts may have been somewhat exaggerated, and reporters have drawn somewhat upon their imagination in their efforts to depict these experiences, yet those who have been long deprived of sleep, and have been obliged to struggle against its mastery day after day, may easily imagine how terrible must be the suffering under such circumstances. And yet, how little this imperative demand of nature and the importance of this great necessity of the brain have been understood, especially in reference to children. When a young man and a student, I well remember hearing some lectures from a person calling himself a physician, in which he took the ground that fifteen minutes was ample time in which to take a regular meal, and that all time spent in sleep in excess of four or five hours at most, was so much lost time; that if persons slept only five hours instead of eight, they would gain more than six years of time in the course of fifty; therefore, every person who was so much of a sluggard as to sleep eight hours instead of five, was responsible for wasting six years in fifty. That ambitious insect, the ant, was held up by the doctor as an example of industry and lofty enterprise, worthy the imitation of everybody who expects to do much in life--as if he knew how many hours that creature is in the habit of sleeping every year. He might almost as well have put his case stronger, and argued that it was everybody's duty to sleep only two of the twenty-four hours, because, forsooth, we would gain more than twelve years in the fifty by so doing. Unfortunately for society, this man has not been alone in advocating such views. There have been others who, in their teachings, have greatly underestimated the importance of an abundance of sleep as a means of securing and maintaining a high standard of health. I think that most persons, especially of the laboring classes, in cities as also in the country, sleep too little. This is true as to adult persons, but to a much larger extent of children, and it is hardly possible to over-estimate the good effects arising from an abundance of sleep upon the brain of the child. There are certain physiological and anatomical conditions existing which tend to show why this is true. 1. The brain at an early age attains a size out of proportion to other organs and members of the body. This is especially true of that portion of the brain supposed to be concerned in mental operations, while those portions whose office is connected with the organic life of the system are less advanced. After twelve or fourteen years of age, the relative rapidity of development as to size becomes changed, and other portions of the system increase more rapidly.