248 RELD — ON MORTALITY. 



ease varies very greatly in its types and results, and also that strong 

 vitality may confer, comparative health, under very unfavorable 

 conditions. 



Another powerful influence that tends to this favorable result is 

 that of habit, for we know that so great is the elasticity and endur- 

 ance of the vital economy that long exposure to a deleterious in- 

 fluence does appear to modify and even arrest its virulence, but in 

 the majority lowered vitality is to be expected with its common 

 result, disease and high death rate. 



In comparing the influence of modern civilization on the Gen- 

 eral Health we have two previous eras to consider — the Ancient 

 and Middle ages. 



Our knowledge of ancient times in this particular is very limit- 

 ed, and if what we have received, be correct, they were more 

 favourable than the present. In ancient times, we have three 

 periods — the first when nomadic life prevailed, and we have reason 

 to believe, the best condition were present. Second, that of the 

 Assyrian and Persian Empires. 



At these times, we have the gradual accumulation of numerous 

 populations at political centres, with a very high average of health, 

 as a rule, if the Chronicles are to be believed ; and this is easily 

 understood, for the great cities of Nineveh and Babylon were 

 totally unlike those that have succeeded them, for they covered a 

 vast area of territory in comparison with population. 



Ihe original founders also devoted great attention to a complete 

 system of drainage and public baths, as well as the perfect cultiva- 

 tion of the soil, with separate location of the domiciles and very 

 wide streets — precisely those conditions that our most recent 

 knowledge would dictate. These methods, no doubt, prevailed 

 then, more from military than sanitary reasons, but it would 

 be scarcely just to say that their educated men had not accurate 

 powers of observation, and were not guided by the experience of 

 life that they must have had even then, although their theoretical 

 explanation might not be so accurate as we can give to-day. It is 

 only fair to assume that, at a time wdien the health and energy of 

 every individual was necessary to the formation of armies, whose 



