We thus learn when we are weak a truth which is less apparent in health, viz., that our available energy is a strictly limited quantity, dependent on nutritive supply. How great, then, is the folly of those who would urge to exertion persons in whom the nutritive supply is defective! But how much greater is the folly of those who, during the early years of the individual’s life, when the constitution is being formed and future health in great measure determined, will persistently compel him to expend his nerve-force in a particular direction, to the detriment of other parts of the organism, or who put such a strain upon the whole that the constitution is permanently injured! The partial injury is perhaps the more dangerous because it is the less easily observed. If a child begins to break down altogether under the stress of his school course, we become aware of the fact, and by timely interference sometimes--not always--put a stop to the work of destruction. But many delicate boys and girls contrive to struggle through their school course with little apparent harm, because the greater amount of their spare nerve-force being attracted to the part on which the strain is put, the allotted tasks can be performed. Whether growth is thereby stunted; whether nerve-force in general be decreased; whether perceptive power be dulled; whether the child have been withdrawn from the active experience of life necessary to healthy development; whether his various physiological needs have been fully supplied--all these questions frequently remain unasked, provided that the child have learnt a specified number of the more or less erroneous notions of his ignorant fellow-creatures, and have put them down on paper. And if he become neurasthenic, or succumb to some complaint to which his lowered vitality makes him fall an easy prey, or if he grow up with feeble powers of observation, or without the self-control dependent on the firm will that can only be developed by means of the right expenditure of a considerable amount of nerve-force, little connection is traced between his defective education and his defective nerve-structure. The children whose education has consisted chiefly of instruction from books cannot properly be said to be educated at all. In most cases their minds are warped by fixed ideas. This is not saying that children should not be taught in the best sense of the word; that they should not be disciplined and trained to self-control, to habits of attention, and to ready observation; that they should not have an intelligent interest awakened in them concerning the universe in which they live. But mere book-learning will never do this. It is, unhappily, possible to be a walking encyclopedia of so-called knowledge, and yet to be an imperfect reflector of the life of our time.