PREFACE. 



author, might be able and willing to compre- 

 hend a part, would turn away in despair from 

 the complexity of the whole. On each Note 

 the reader will of course pause, draw his own 

 inferences, and acquiesce or dissent according 

 to the degree of conviction they impress on his 

 judgment. Some have been inserted more to 

 stimulate curiosity and promote discussion than 

 as established truths ; for a valuable hint may 

 be thrown out by one incapable of forming a 

 regular system, and as the mind expands we 

 gradually discover how much remains to be 

 known. 



