CHAPTER I 



THE PRINCIPLE OF CONTINUITY IN LIVING AND 

 NOT-LIVING MATTER 



BIOLOGY studies those characters which are common to 

 all living beings whether animal or vegetable, and which, 

 taken together, are wanting in not-living bodies. If we 

 define life by taking the sum total of these common char- 

 acters, it is evident that we ought never to find all of the 

 characters in any not-living body. Otherwise our definition 

 would be worthless. 



Living beings have to be recognized among other natural 

 bodies by this sum total of characters defining life, just 

 as alcohols are known from other chemical bodies by their 

 possessing all the characters which define the function 

 alcohol. But this is not a reason why the differences which 

 separate living bodies from not-living bodies should be more 

 important than those which distinguish alcohols from al- 

 dehydes or amines. It may seem childish to insist on so 

 evident a truth ; but it is not useless because of the per- 

 sistence, if not in science, at least in current language and 

 literature, of old mystic ideas which preceded the advent 

 of the scientific period of history and humanity. 



When the study of living beings is carried out in a scien- 

 tific manner, that is, by registering all their objective pro- 

 perties, we do not need to remember that we are alive our- 

 selves ; and we arrive at an objective definition of life as 



