4 PEEFACE. 



and action ; and third, their application to, and connection 

 with, the common affairs of life. 



The first is limited, and is only preparatory to the second. 

 The second also is limited, and subordinate to the third. 

 The last is almost infinite in extent and variety, and requires 

 much study. 



In sustaining the body with food, and drink, and air, 

 in defending it with clothing and shelter, in the use of 

 our muscles and brain, in applying the body and the 

 mind to whatever purpose, we use some or all of our 

 organs ; and the health and strength, or pain and weakness, 

 the good or the evil consequences, must be in accordance 

 with the wisdom and faithfulness with which we govern 

 ourselves in these matters. Therefore the knowledge of 

 the Physiological Laws, and of their requirements, becomes 

 of practical importance in every moment, and in all the 

 circumstances of our being. 



This book, in a somewhat different form, was formerly 

 published under the name of Practical Physiology. But as 

 the main purpose of the work was to teach the Laws of 

 Health, and as the whole of it has been revised, and much 

 of it re-written, the title is changed to PHYSIOLOGY AND 

 OF HEALTH, which better describes the work. 



EDWAED JARVIS. 

 DORCHESTER, MASS., September, 18C5. 



