That many of the conditions pertaining to modern civilization prove to be highly conducive to physical diseases, needs hardly to be said, and that they are no less productive of insanity and other diseases of the nervous system, will be evident from some considerations to be alluded to in connection with this discussion. 1. At first thought it might appear that the development and extension of civilization, which carries with it so many and great advantages in many other respects, should also be favorable to mental health. It is a law of the human system that the various organs become strong and maintain a high standard of health, only while under a considerable degree of activity, and this is especially true of the muscular and nervous systems. Inactivity and disuse tend toward degeneration, therefore, such circumstances and surroundings of life as will conduce to harmonious activity of these organs and parts, would, _ceteris paribus_, be most favorable to health. Now the various portions and faculties of the human brain are brought into a state of full development and activity only under the conditions and influences of civilization; all of those higher and finer manifestations of thought, sentiment, and feeling, which pertain only to man; the satisfaction which comes from the results of mental activities both in relation to mechanics, education, governments, and the social amenities; the increase of strength pertaining to thought, and consequent self-reliance, and ability to rise above the adverse circumstances and experiences of life; freedom from the conditions of uncertain and limited supply, with attainment of those of a fairly certain and abundant character; the results which come from travel, and intercourse with persons of other nationalities; from trade, commerce, and intellectual pursuits; together with the possession of knowledge, which is power,--all come only from the conditions and influences of civilization, and should rather have a tendency to confirm and make strong mental health. And this would undoubtedly be the result, if these were all, or indeed mainly, the effects attendant on living under the influences of civilization. But, unfortunately, these are only some of the beneficent results of this change. Other influences, customs, and practices, and those of a character highly adverse to the maintenance of healthy mentality, have also come into operation, to a greater or less extent, and are especially potent in modern civilization.