Above all other classes of men, it is certainly important that physicians and medical men generally should be thoroughly educated in sanitary knowledge. The authority which they possess, and their opportunities for instilling this knowledge when families are keenly alive to the dangers of illness, would give them greater success as health missionaries than any other class of society. But medical men are not taught that it is equally their duty to prevent disease as to cure it; and their attention is not, therefore, sharpened to observe and to deprecate the numerous habits in family life which tend to produce disease. There are but two chairs of hygiene established in connection with our medical schools, and attendance upon those lectures is not obligatory--_i.e._, is not essential to the attainment of a degree. Every practical instructor knows that the press of studies is so great that the student always neglects whatever is not absolutely necessary to his success. One of the most beneficial changes that could be introduced into medical education would be the establishment of hygiene as a first-class chair, of equal importance with anatomy, a searching examination in its teachings being indispensable to the attainment of any degree which gives authority to attend the sick. Almost equally important is the introduction of sanitary instruction into theological seminaries. The clergy generally seem to be sadly ignorant of the laws of health. The powerful and legitimate influence which they exercise would be more valuable if it were not so one-sided. If the clergy all over the land, who command a mighty army of parish visitors, could show those visitors the direct and positive connection between pure blood (made out of food, light, and air) and pure thought, what a revolution would be wrought in every country village! But the clergy themselves must be educated in such knowledge, for it is not simply intellectual assent, but a thorough realization of it that is necessary. The same knowledge is as necessary to our schoolmasters. No one is fit to direct the education of youth who does not perceive the difference between the young and the old, and suit education to the child’s nature and not to his own. The kind of studies, their variety, frequent movement, and change, the arrangement of schoolrooms, the unlimited supply of fresh air, the playground, etc., must all be based upon an acquaintance with sanitary knowledge, which would be a proper subject for examinations and certificates.