PREFACE 



A LARGE portion of this book appeared some 

 ten years ago under the title of What is Life, 

 and met with a very favourable reception, but 

 has begun to exhibit tendencies of being out of 

 date, owing to the large number of books and 

 papers on the subject with which it dealt which 

 have been published since it saw the light. 



The present issue includes the greater part 

 of the former work with new matter in response 

 to the need mentioned above, but with some- 

 thing more. In some of the very valuable 

 books which have been published on the side 

 of Vitalism during the past ten years, there 

 have been given accounts of the history of the 

 conflict between vitalists and anti-vitalists 

 throughout the centuries, but without excep- 

 tion these ignore or almost ignore the position 

 towards the subject assumed by the Philo- 

 sophers of the School. I cannot understand 

 still less excuse this neglect, and it has been 

 a part of my object to deal with an aspect of 

 the controversy which has been thus, as I 

 think, unjustly neglected. The former work 

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