It is most important that a clear distinction should be preserved between these adult cases and those which date from birth or childhood. The former are labouring under _dementia_, not _amentia_. They are demented persons, or, as they are called in our asylums, dements. They are not always, but they are for the most part, harmless lunatics. It is confusing to call them imbeciles, now that this term has become restricted by medical writers to those who are, or once were, feeble-minded children. There are, of course, all degrees of mental defect possible at birth or in childhood, between that of the most degraded idiot and of a child who is said to be not very bright. With a large majority, however, something can be done to improve the mental condition, whereas with demented persons there is no ground for expecting improvement. The past history of the condition and treatment of idiots differs in some respects widely from that of the insane. Happily in many countries, especially in the East, they have been regarded as objects of special affection and care--as sacred beings possessing a certain weird, if not divine, element in their nature. Though helpless and involving much trouble, they do not exasperate or terrify their relations in the same way as the furious maniac. As a rule, they do not suggest the same exercise of force and use of fetters as the ordinary lunatic. Still, in many instances, no doubt, weak-minded and wayward children have been harshly treated and beaten. But whether regarded as specially favoured by Heaven, or treated as stupid children, they were never subjected to any special training for education until recent times.