BIOLOGY IN HUMAN AFFAIRS 



ideal set of rules, they will be able to avoid illness and 

 become or remain healthy. Undoubtedly they would further 

 assume that if all individuals did the same, disease would 

 disappear. This of course is an incorrect generalization 

 based upon a part truth. Hygienic living by individuals is 

 highly desirable, and tends to reduce their liability to 

 illness, and their menace to others. It is one of the objectives 

 of public health work to secure the observance of personal 

 health practices by individuals. On the other hand, there 

 are numerous factors in the induction and transfer of disease 

 which cannot be dealt with by individual effort, at least 

 not practically or economically. The man who lives in a 

 community where malaria is prevalent may observe 

 hygienic rules, dose himself with quinine, and stay behind 

 screens after dusk, and he may thus for a period, and at 

 considerable sacrifice, avoid infection; but in the long run 

 he is likely to overlook some loophole in the scheme and 

 come down with chills and fever. On the other hand, by 

 well-directed community effort it is often possible to 

 eradicate the infection from the area, so that no person 

 living there, even if his personal habits were careless, 

 could acquire the infection. Against typhoid fever again, 

 public health measures, such as the providing of safe water 

 and milk supplies and sewage disposal, insure a cheaper, 

 more certain, and more general protection than could ever 

 be expected from the exercise of individual precautions 

 by members of the population concerned. Again, in the 

 case of some pestilences such as yellow fever and bubonic 

 plague, the individual could hardly secure immunity 

 except at the sacrifice of nearly all other activity, while 

 public measures can be counted upon for speedy control of 

 epidemics. 



We have in the ancient Hebrew sanitary measures com- 

 monly attributed to Moses an excellent example of rules 

 for personal health which, while limited in scope and often 



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