As stated in the chapter on etiology, amongst the many causes of mental disease may be distinguished some few that are essential from others that are merely incidental or contributing.
There are few persons, if indeed there are any, who are so fortunate as to go through life without being repeatedly subjected to the influence of some of the incidental causes: the prevention of mental disorders will consist largely in measures for combating the essential causes - heredity, alcohol and drug addictions, syphilis, and head injuries.
Measures for the prevention of mental disorders may be undertaken by the individual or by society. As far as the average healthy individual is concerned the measures are few and simple; it must, however, be noted as a fact which has been repeatedly demonstrated under the most varied conditions, that the great mass of individuals, even if made fully aware of all dangers, will not practice preventive measures in any systematic manner; this is perhaps due to a curious trait of human nature owing to which men are disinclined to believe that any evil may befall them and therefore have a tendency to take chances; further it must be remembered that the great causes of mental disorders appear in the shape of strong temptations which are difficult and for some impossible to resist. However this may be, those who are concerned with the problems of prophylaxis in psychiatry would be impractical if they relied entirely upon dissemination of knowledge on this subject among the people with the hope of thus reducing to a material extent the incidence of mental disorders.
Dissemination of knowledge should, we believe, be regarded as a preliminary step which will make possible the application of large measures by society as a whole - for nothing short of such measures will constitute an effective system of mental hygiene.
1 A. J. Rosanoff. Causes and Prevention of Insanity. The Long Island Med. Journ., Sept., 1915.