PREFACE. Vll 



In looking at any example, or mode of 

 expression, processes of analysis are used till 

 we get at such elements of the phenomena 

 as are capable of physical inquiry, and whose 

 relations may be demonstrated. 



Biology, medicine, and philosophy, with 

 their working hypotheses, are drawn upon 

 for facts, analogies, and arguments. I have 

 aimed at practical results rather than intellec- 

 tual satisfaction alone, hoping thus to assist 

 those engaged in scientific work and others 

 engaged in social life. 



The general scheme and purport of this 

 work may be gathered from the first chapter ; 

 the more practical and illustrative descrip- 

 tions are contained in chaps, viii. to xiv. 

 Summaries are appended to certain of the 

 chapters (see index). 



The chapter on Art Criticism illustrates the 

 principles and arguments used throughout the 

 work : as this may possibly be read by some 

 without the preceding chapters, the principles 

 of analysis of expression are here repeated ; 



