Healthy vigour is another essential to healthy growth, whether of the brain or of the body; but, from general ignorance of physiology, this has been, and still is, equally disregarded in the treatment of the young. In our public schools, the whole pupils of a large class are set to the same task, and undergo precisely the same confinement and absence of wholesome bodily action. It matters not whether they be robust or weak, indolent or vivacious, fond of play or fond of books. It never occurs to us that what may be sport to one is a heavy burden to another; and that the length of confinement, and absence of food, which a robust boy can withstand, may seriously injure one of a weaker constitution. It is needless to add, that nothing can be less in accordance with the dictates of a sound physiology than the ordinary arrangements of our schools; and, judging from the very inadequate results with which so much labour is repaid, and the very indifferent health which attends it, it may be inferred, that no discipline can be less in accordance with the laws of nature, or less available as a means of improving the minds and brains of those who are subjected to it. The young, on account of their growing and rapid nutrition, stand doubly in need of a pure and bracing air, and of ample muscular exercise out of doors; and yet, so entirely is this condition disregarded in our plans of education, that in the winter the whole day is spent in the close and corrupted atmosphere of the school, and the exercise is restricted to little more than walking to and from it. It is in vain to think that the brain is not injured in its development, and the mind not weakened in its powers, by this neglect. The brain partakes in the general qualities of the constitution. If the body be imperfectly nourished and supported, the brain is weakened in common with the rest of the system, and the mind is retarded in its progress, and often impaired in vigour, by otherwise inadequate causes.