PREFACE. V 



ing in nature. If it be found to express a fact, other 

 lines of thought must determine its significance. 

 No law is self-sufficient, and evolution no more ex- 

 plains itself than does the law of gravitation. 



The arguments advanced in these pages are, with 

 few exceptions, such as may be found elsewhere in 

 the various discussions upon the subject. I do not, 

 however, consider it desirable to give authorities, 

 since the arguments have by this time become the 

 common property of the world. These arguments 

 I shall try to state as fairly as possible ; and when a 

 direct statement is made, it may be understood as 

 one which is almost, if not universally, acknowl- 

 edged. It is of course impossible wholly to elimi- 

 nate the factor of personal opinion ; but in most 

 cases the conclusions drawn are those which have 

 been arrived at by students in general, and are not 

 the opinions of individuals. 



