Perhaps no subject has been more fully dwelt upon than the danger of great intellectual activity for girls at this youthful period of life, and it has come to be thought that an idle brain insures a healthy body. But nothing can be more false. The brain, as the ruling organ of the body, requires a healthy, rich development; and this can only be secured by regular exercise and training, fully using but not overstraining its powers. The usual accompaniments of intellectual study are the cause of this false prejudice. Close school-rooms, late hours of study, restless excitement from over-stimulated ambition, have no necessary connection with intellectual progress. Much of the evil effect of schools comes not from too much intellectual activity, but from too little; from listless hours spent over lessons which under good conditions could be learned in half the time. Mental action, continued after the brain is weary, or when it is not nourished by fresh blood, or under any disadvantages of physical condition which prevent it from being easy and delightful, will injure the system; and will prove a waste of mental power as well as of physical health. The greatest lesson that we have to learn in our mental life, is to value quality of work more and quantity less. Everybody knows how much more exhilaration and less fatigue is experienced from a brisk walk, than from standing listlessly around for double the length of time; and it is just so with mental effort. We want neither feverish, excited work, nor lazy work; but earnest, hard, vigorous effort, ceasing when the brain is weary or the object is accomplished.[30] I have yet to see the first proof in man or woman, that well-regulated activity of the brain injures the health. I have known many instances where vigor of body was restored by earnest mental life; and I believe that more young women sink into invalidism, or die prematurely, from the want of adequate thorough mental training, than from any other one physical or mental cause. For we must remember that the brain craves thought, as the stomach does food; and where it is not properly supplied it will feed on garbage. Where a Latin, geometry, or history lesson would be a healthy tonic, or nourishing food, the trashy, exciting story, the gossiping book of travels, the sentimental poem, or, still worse, the coarse humor or thin-veiled vice of the low romance, fills up the hour--and is at best but tea or slops, if not as dangerous as opium or whisky. Lord Bacon says most truly: "Too much bending breaks the bow; too much unbending, the mind." After labor, rest is sweet and healthful; but all rest is as dangerous as all labor.