THE INSTINCT OF SURVIVAL 115 



of life, would have a potent influence in compelling 

 the important changes which education and legisla- 

 tion could effect. 



If science has not yet formally given us the final 

 rules for attaining the utmost longevity, she has 

 made clear one guiding principle. It is that we 

 cannot hope for any specific recipe for long life, 

 but rather that the prolongation of our days is to be 

 reached through the evasion of that multiplicity of 

 hurtful influences which, taken together, impair the 

 bodily machinery in sufficient degree to rob man of 

 some portion of the life that was possible to him in 

 view of the potentiality inherent in his organization. 

 According to this view, the lengthening of life in 

 general must be attained through a wide knowledge 

 of physiological processes, and through an intelli- 

 gent application of this to the needs of each indi- 

 vidual. 



It seems worth while to consider the injurious 

 influences that curtail human life, since the control 

 of them is the key, not merely to longevity, but also 

 to greater efficiency and greater happiness, through 

 the prevention of disease. And in any discussion of 

 the prolongation of life, the consideration of the 

 theme of maintenance of health, physical and men- 

 tal, is quite unavoidable. 



It has long been customary to make a sharp dis- 

 tinction between the things that injure the body 

 and those that injure the mind, and this separation 

 is still serviceable, notwithstanding the fact that 



