In psychoneuroses developed in persons of previously normal brain-function heredity is only a latent predisposing cause. The tendency is to recovery; relapses are infrequent. They are not so readily transmitted to later generations. The disease follows the course of some well-defined type. There is not a tendency to periodicity. Delusions arise chiefly from psychological sources as the result of diseased mental conditions. They are usually not early symptoms, and in general they correspond with the prevailing state of the mind. Delusions correspond with the mental state. The change from health to disease is well defined. These are the main features of the two classes of mental disease, but the line between them is not a hard and fast one, and it is not seldom impossible to place a particular diseased person definitely in the one or the other. The objection to all of the classifications of insanity now in use, that they have not an accurate scientific basis, and that a diagnosis must often be delayed or changed as symptoms develop, applies, although in a less degree, to other diseases than of the mind. HISTORY.—The history of insanity is probably as old as the human race, although its rarity among savage nations at the present day, and its greatest prevalence where there are the widest extremes of wealth and poverty, indicate that it is essentially a disease of the high civilizations. It is found even in the lower animals. It is described in the early writers on medicine from Hippocrates and Plato down. The ancient Egyptians had temples dedicated to Saturn, where they cared for the insane with music and dancing. The Greeks and Romans treated the sick, and probably some of the insane, in rooms adjoining their temples. The monks of Jerusalem built an asylum for the insane of their number in the sixth century. There were several asylums in existence among the Moors in the seventh century, and it is thought that at the time of their invasion of Spain they introduced them into Western Europe. The monks, who were the chief depositaries of medical knowledge in the Middle Ages, treated the insane, as they did to a less extent each other, by flagellations, until St. Vincent de Paul and the Knights of Malta proclaimed insanity a disease and treated it as such. It would be idle to estimate how many were put to the rack, burned, and otherwise maltreated as possessed of the devil or as witches—how many were called prophets or saints.