10 INTRODUCTORY REMARKS. 



Something valuable, it is thought, can be added to what is 

 already of great intrinsic merit, by both illustration and presen- 

 tation. This is made conclusive by the frequently and urgently 

 expressed desire of teachers, well qualified to judge, that for 

 their own and pupils' use the subjects should be presented in 

 book-form, according to the methods that had given satisfaction 

 when orally used before them and their classes. 



These methods are neither so novel nor so extraordinary as 

 to render useless any previously acquired familiarity with the 

 subject ; they merely make it more familiar by presenting known 

 facts and ideas in a new light and with new features, in groups 

 and relations suggesting new thoughts, removing obscurity, and 

 exhibiting a unity and completeness highly satisfactory. 



The art of producing the desired and gratifying result does 

 not consist in the use of a single idea or one means only. The first 

 and most essential idea to be kept in mind is, that, if possible, 

 the reasons for the existence of any part should be pointed out 

 before its structure is described ; for, if the necessity for it, and 

 what ought to be, is first shown, the description of the structure 

 and its adaptation to use will be much more interesting and 

 very easily understood. 



Physiology naturally precedes Anatomy in the order of 

 constructive thought. Purpose is always antecedent to construc- 

 tion, which is governed by and in accordance with purpose. This 

 is the Creative idea and mode of thought, and also the most 

 natural and delightful to the human mind. It is the key to the 

 great charm that always abides in the study of Natural Theology. 



Functions are not performed because certain parts exist, but 

 conditional parts exist because certain functions must be per- 

 formed : function is therefore always the object in view as the 

 result ; and how to perform it perfectly, with the greatest econ- 

 omy of time, space, and material, is the sub-necessary question. 



Unfortunately, though the general purposes and the modes 

 and results of action of the various parts of the body are known, 



