XI INSTRUCTION IN PHYSIOLOGY 297 



and how to influence tliem towards the mainte- 

 nance of health and the prolongation of life; the 

 business of the general public is to give an intelli- 

 gent assent, and a ready obedience based upon 

 that assent, to the rules laid down for their guid- 

 ance by such experts. But an intelligent assent 

 is an assent based upon knowledge, and the knowl- 

 edge which is here in question means an acquaint- 

 ance with the elements of physiology. 



It is not difficult to acquire such -knowledge. 

 What is true, to a certain extent, of all the phys- 

 ical sciences, is eminently characteristic of physi- 

 ology — the difficulty of the subject begins beyond 

 the stage of elementary knowledge, and increases 

 with every stage of progress. While the most 

 hif^hlv trained and the best furnished intellect 

 mav find all its resources insufficient, when it 

 strives to reach the heights and penetrate into the 

 depths of the problems of physiology, the elemen- 

 tary and fundamental truths can be made clear 

 to a child. 



■ No one can have any difficulty in comprehend- 

 ing the mechanism of circulation or respiration; 

 or the general mode of operation of the organ of 

 vision; though the unravelling of all the minutise 

 of these processes, may, for the present, baffle the 

 conjoined attacks of the most accomplished ph3'Si- 

 cists, chemists, and mathematicians. To know the 

 anatomy of the human body, with even an ap- 

 proximation to thoroughness, is tlie work of a 



