ORIGIN AND NA TURE OF LIFE. 323 



seminal forces, as the Scholastics taught, disposed 

 matter for the assumption of all the multitudinous 

 forms into which it subsequently developed. 



The Nature of Life. 



Respecting the real nature, not the origin, of 

 life, there have, indeed, been many and diverse opin- 

 ions. Even now it is almost as much of an enigma 

 as it was in the days of Aristotle, and we are at pres- 

 ent, apparently, no better qualified to give a true 

 definition of life than was the great Stagirite, twenty- 

 five centuries ago. Living beings can, indeed, be 

 distinguished from non-living beings by their struc- 

 ture, mode of genesis, and development, but this 

 does not help us toward a clear and precise defini- 

 tion of life. 



According to the philosophers of antiquity there 

 was a certain independent entity, or vital principle, 

 which, uniting with the body, gives life, and, separat- 

 ing from it, causes death. Plato and Aristotle, as is 

 well known, admitted the existence of three souls, or 

 animating spirits, the vegetative for plants, the vege- 

 tative and sensitive for animals ; and for man, an in- 

 telligent and reasoning spirit in addition to those 

 possessed by plants and animals. 



Paracelsus and Van Helmont spoke of the prin- 

 ciple of life under the name of arch&us, and at- 

 tempted to explain vital functions by chemical 

 agencies. Others, still, " made the chyle effervesce in 

 the heart, under the influence of salt and sulphur, 

 which took fire together and produced the vital 

 flame!" 



