TO THE TEACHER. XV 



We meet difficulties at every step if we have not studied the 

 details of circulation and nervous and muscular action. 



The nerves control not only the muscles, but every activity 

 of the body. They are the key to the whole mechanism. Why 

 should we leave the study of their work to the very last, 

 especially since we know that whatever is last in a book is 

 likely to be gone over hurriedly ? 



Throughout the book the natural sequence of topics has 

 been studied with care, and the relation of one part to another 

 kept in mind. 



The order adopted is the result of twenty years' experience 

 in teaching this subject. After trying almost every possible 

 order this one seems to offer the " least resistance " to the 

 progress of the pupil. The effort of the teacher should be so 

 to arrange the topics that the easiest should come first and 

 thus readily lead the way to the next, as the first step of the 

 stair makes it more easy to reach the step above it. 



There is no royal road to learning ; it is up-hill work at 

 best ; but the teacher has no right to try to lead the pupils up 

 the precipitous side of a mountain if there is a side where the 

 slope is gradual, where a relatively easy and natural path may 

 be made. 



" Instruct us where the mountain low declines, 

 So that attempt to mount it be not vain. 

 For who knows most, him loss of time most grieves." 



DANTE. 



