LETTER IV. 



THE CRUCIFEROUS TRIBE DOUBLE FLOWERS THE 



VIOLET TRIBE — METHOD OF ANALYSIS. 



(Plate IV.) 



1 AM pleased, but not surprised, to find from your 

 last letter, that Botany dees not prove, upon exami- 

 nation, to be either so dry and technical a science as 

 you imagined, or so little related to objects of daily 

 interest, as others had persuaded you. Depend upon 

 this truth, before all others, that knowledge is always 

 useful, and that when we are unable to discover its 

 utility, we have to blame our own short-sightedness, 

 or incapacity, or any other cause, rather than know- 

 ledge itself. 



Sir John Herschel, in that admirable treatise of his 

 which should be in the hands of every human being 

 who has arrived at an age to be capable of under- 

 standing it, — Sir John Herschel has well remarked 

 that, " the question to what practical end and advan- 

 tage do your researches tend ? is one which the spe- 

 culative philosopher, who loves knowledge for its 

 own sake, and enjoys, as a rational being should 

 enjoy, the mere contemplation of harmonious and 

 mutually dependent truths, can seldom hear without 

 a sense of humiliation. He feels that there is a loftv 



