But sometimes, the over-tasked mind leads to mischief which Nature cannot rectify; an attack of water on the brain destroys the child, or if not it sinks under almost any accidental disease. In other instances neither of these results takes place, but the whole nervous system seems profoundly shaken, and the moral character of the child seriously, and even permanently injured. I remember a quick and clever little girl aged five and a half years who was urged on by her governess to work which she delighted in, till at length the signs of over-taxed brain showed themselves in frequent extreme irritability, and occasional attacks of causeless fury amounting almost to madness. It was fully a year during which almost all mental work was suspended, while the child was sent to have complete change under most judicious management in the country, before her mind quite recovered its balance and she became able to resume her studies in a very moderate degree. Cases such as this are instances of the slightest degree of a condition which if not remedied may pass into confirmed insanity. I believe the gradations to be almost imperceptible by which the one state passes into the other; and I have known instances in which the ungovernable temper and occasional fury of the child have passed in youth into abiding insanity which rendered the patient the inmate, and I fear the permanent inmate, of a lunatic asylum. In whatever circumstances insanity comes on in childhood, and it does sometimes, though very seldom, come on independently of any obvious exciting cause, it always assumes the character of what has been termed moral insanity, or of that condition in which the moral system rather than the mental power is chiefly disordered. Idiocy is unquestionably of much more frequent occurrence in childhood, than any of those forms of mental or moral disorder of which I have been speaking hitherto. The term idiocy, however, is a very wide one, including conditions differing remarkably from each other both in kind and degree, while not seldom it is misapplied to cases in which there is mere backwardness of intellectual power.