The mental diseases that are of special interest in this respect are the so-called idiopathic insanities. Idiopathic is a word we medical men use to conceal our ignorance of the cause of disease. Idiopathic diseases are those that have come of themselves, that is, without ascertainable cause. As a matter of fact, the most important group of mental diseases develop without presenting any alteration of the brain substance, so far as can be detected by our present-day methods of examination. The initial symptoms of these diseases, then, are of great importance, and not readily recognisable unless looked for especially. There is no physical change to attract attention, and the change of disposition and mental condition is often insidious and only to be recognised by some one who is in the confidence of the patient. It is in these idiopathic insanities, then, that the careful observation of the clergyman is of special significance. Needless to say, powers of observation to be of service must be trained.
While there are no known changes in the brain tissues in these diseases, it seems not improbable that the development of our knowledge of brain anatomy, which is especially active at the present time, will very soon demonstrate the minute lesions that are the basis of these mental disturbances. It seems not unlikely that the underlying cause of so-called idiopathic insanity is usually some change within the brain cells. Hints of the truth of this conjecture are already at hand. Meantime the actual observation of this class of patients in asylums and institutions, private and public, and the collation of the observations of authorities in psychiatry from all over the world, have thrown a great deal of light on these forms of mental disease. We know much more of the initial symptoms and of incipient conditions that threaten the development of mental { 213} disequilibration than we did twenty-five years ago. With regard to prognosis especially, recent publications have added considerably to our knowledge, although it must be confessed that they have rendered our judgment of such cases much less hopeful.
The ordinary forms of mental diseases have sometimes been considered as passing incidents in the lives of patients suffering from such disorders. While it was generally understood that severe cases were apt to have recurrences, and that after persistence of mental symptoms for a certain length of time the outlook as regards eventual absolute cure is rather dubious, yet the general prognosis of such simple states as melancholia or simple mania was not considered to be distinctly unfavourable. Patients might very well recover their mental sensibility after even a severe attack, and never have a relapse.