70 LETTERS TO BROTHER JOHN. 



LETTER III. 



224 Blackfriars Road, 



15th March, 1836. 

 MY DEAR JOHN, 



I HAVE already described to you as much of the 

 structure of the body as I believe necessary, in 

 order to enable you to understand the nature of 

 the several actions which are perpetually going on 

 within that structure. It is of these actions that I 

 have now to speak. But, previously to a description 

 of the actions peculiar to living beings, it seems 

 proper to devote a few moments to an inquiry into 

 the nature of life itself. 



Writers on physiology* are accustomed to enu- 



* Physiology is an exceedingly improper term. It is used 

 by the moderns to signify the science of life ; animal physio- 

 logy being used for the science which treats of the life of ani- 

 mals, and vegetable physiology being appropriated to the science 

 of life in vegetables. But the term Physiology no more de- 

 notes the science of life, than it does the science of picking 

 pockets. It means the science of nature ; and it is as strictly 

 applicable to the laws which govern inanimate matter, as to 

 those which regulate the actions of living beings. The term, 



with 



