The science and the art of 1) preventing disease; 2) prolonging life; and organised community efforts for a) the sanitation of the environment; b) the control of communicable infections; c) the education of the individual in personal hygiene; d) the organisation of medical and nursing devices for the early diagnosis and preventive treatment of disease; and e) the development of the social machinery to ensure everyone a standard of living adequate for the maintenance of health, so organising these benefits as to enable every citizen to realise his/her birthright of health and longevity.