INTRODUCTION 



The consequence of the progress of Science is the gradual 

 weakening of all the primary concepts born of ignorance. Their 

 only strength lies in the unknown, and as that is gradually 

 elucidated quarrels must cease, divergent doctrines must fade 

 away and be replaced by scientific truth which will reign supreme. 



Claude Bernard (1875) 



The problem of life has always passionately interested man. 

 And yet there has never been a satisfactory definition of 

 life. Why is this? Perhaps because a distinction must be 

 drawn, as Claude Bernard pointed out, between the word and 

 the thing itself. Pascal, who so well understood all weaknesses 

 and illusions of the human mind, points out that in reahty 

 true definitions are creations of the mind, or definitions of 

 namesy and merely conventions for shortening speech. But 

 he admits that there are primitive words which are under- 

 standable without need of definition. According to Claude 

 Bernard, the word 'life' is one of these. Everybody com- 

 prehends the words 'life' and 'death'. It is impossible to 

 separate these two terms, for what lives will die, and what is 

 dead has lived. 



Ideas on Hfe have necessarily varied with different epochs 

 and according to scientific progress. The reader may remem- 

 ber the purely verbal definition of the Encyclopedia: 'Life is 

 the opposite of death', and that of Bichat: 'Life is the com- 

 bination of functions which resist death.' In other words 

 life is the combination of the vital properties which resist the 

 physical properties. This is a vitalis tic view. It was generally 

 thought that Claude Bernard meant to give a definition of 

 life when he wrote: 'Life is Death.' But this is not quite 

 true for, in a later article, this phrase is preceded by another 

 which is usually overlooked and which materially restrains its 

 meaning: 'If we wished to express the fact that all vital 

 functions are the necessary consequence of organic com- 

 bustion, we would repeat what we have already stated: Life 



