VI 



PREFACE. 



insipid by the general reader, accustomed 

 to the luxuries of modern literature^ the 

 author has not scrupled to mix with it such 

 collateral matter as he thought might serve 

 to correct the aridity. The very great in- 

 terest of the question regarding species, 

 variety, habit, has perhaps led him a little 

 too wide. 



There is one advantage in taking a sub- 

 ject of this kind, that few professional (li- 

 terary) critics can meddle with it, further 

 than as regards style and language, with- 

 out exposing their own ignorance. Yet 

 will the author experience the highest 

 pleasure in being instructed and corrected, 

 wherever his knowledge may be found de- 

 fective, or when speculation or misconcep- 

 tion of facts have led him into error. Know- 

 ledge and truth, is mental strength and 

 health ; ignorance and error^ weakness and 



