If the views presented in the preceding chapter and also in this, in reference to the tendency of insanity to increase, and which statistics appear to confirm, are correct, we perceive at once how important, in relation to both political economy and the future health and happiness of society, becomes the problem of this disease. As a subject of science and philanthropy, it has for some years engaged the study and interest of many who have been desirous more fully to understand its bearing in both these respects; but in the no distant future, it will become the disease of paramount importance and interest to legislators and political economists; and as there exist reasons for supposing that, under the changing conditions of our modern civilization, it will more surely tend to invade the homes of many who have heretofore been exempt, and will in the future even more surely than in the past, affect all ranks and conditions of society, the increasing importance of making its causes a subject of investigation, and of endeavoring to prevent its increase, even in a limited degree, becomes at once apparent. It may be remarked at the outset that many of the _exciting_ causes of insanity are uncontrollable. We can do little, or nothing, toward changing or modifying the demands which are made upon us by the business operations of the present; nor toward modifying those great activities which are so loudly calling for development and conduct in life; we cannot do much toward changing the unequal conditions which pertain so largely in relation to property, occupations, and modes of living; or in avoiding the sufferings which result from the bereavements and disappointed expectations of life; we cannot, nor is it desirable, in all respects, if we could, do much to promote community of interests in property. But it is important to bear in mind that, after all, the prime condition of insanity lies, to a large extent, back of these exciting causes. Thousands have passed through such conditions and experiences, have suffered from disappointment and failure in respect to their plans and purposes; have endured exposures and hardships all their lives; all, without becoming insane, and thousands more will continue to do so in the future. It is evident, therefore, that there must exist back of these experiences, a state of the nervous system which renders it susceptible of the disease. This, it is, which is the prime factor in the problem of insanity; and it becomes of the first importance to discover, so far as we may be able to do so, in what this predisposing tendency may consist, or, at least in what ways, or through the operation of what causes, it more especially tends to come into existence and operation to so large an extent at the present time, and by what means it maybe avoided.