The period of early childhood--say up to seven or eight years of age--is that during which the brain and other parts of the nervous system are most actively developing, in order to fit them for the great work before them. It is safe to say that the only instruction given during this time should be that which consists in teaching children how to observe. The perceptive faculties alone should be made the subjects of systematic attempts at development. The child should be taught how to use his senses, and especially how to see, hear, and touch. In this manner, knowledge would be acquired in the way that is preeminently the natural way, and ample food would be furnished for the child's reflective powers.--DK. WM. A. HAMMOND, _Popular Science Monthly, November, 1884_. _Reserve Force_.--The part which "a stock of energy" plays in brain work can scarcely be exaggerated. Reserves are of high moment everywhere in the animal economy, and the reserve of mental force is in a practical sense more important than any other....Without this reserve, healthy brain work is impossible. Pain, hunger, anxiety, and a sense of mind weariness, are warning tokens of exhaustion. When the laborious worker, overcome with fatigue, "rouses" himself with alcohol, coffee, tea, or any other agent which may chance to suit him, he does not add a unit of force to his stock of energy; he simply narcotizes the sense of weariness, and, the guard being drugged, he appropriates the reserve....Meanwhile, the effort to work becomes daily more laborious, the task of fixing the attention grows increasingly difficult, thoughts wander, memory fails, the reasoning power is enfeebled; physical nerve or brain disturbance may supervene, and the crash will then come suddenly, unexpected by on-lookers, perhaps unperceived by the sufferer himself.