When our President invited me to contribute a paper for this meeting, I understood that it was to be of the nature of a presentation of the case of the school medical officer in relation to a unification of those medical services which deal with the various aspects of mental defect. This I have attempted to do in the belief that if real constructive work is to be done, the foundations must be laid by examining the problem as it is manifested in childhood and early youth. This is comparatively easy, because not only does a very large proportion of children and young persons now come under continuous medical observation, but there is in addition the important testimony which their educational progress affords as to their mental make-up. Further, I believe that the practical solution of the question of mental deficiency from the point of view of the community at large will depend for its completeness upon early diagnosis, and upon the measures which are taken to deal with the subjects before they reach adult life. In one of his addresses, Dr. Oliver Wendell Holmes urges that in these days of specialisation we must not neglect the older theories which have yielded place to new. “The débris of broken systems and exploded dogmas form a great mound, a Monte Testaccio of shards and remnants of old vessels which once held human beliefs. If you take the trouble to climb to the top of it, you will widen your horizon.” To none is this advice more needful than to those of us who are brought into contact with mental defect and all its attendant problems. There is still so much confusion of thought, the result of changing points of view, that we do not always see clearly the end to which our efforts should be directed. This is of practical importance, because upon the standpoint from which we view the problem will depend, not only the range of our activities, but also the particular members of the community whom we hope to include therein.