256 BOTANY. 



young to seek for new abodes ; and the rivalry of the 

 males in many kinds prevents their crowding the one 

 on the other. Whether the swallows and house- 

 martins return in the same exact number annually is 

 not easy to say, for reasons given above ; but it is 

 apparent, as I have remarked before in my Mono- 

 graphics, that the numbers returning bear no manner 

 of proportion to the numbers retiring. 



LETTER LXXXII. 



TO THE SAME. 



SELBORNE, June 2, 1778. 

 DEAR SIR, 



THE standing objection to botany has always 

 been, that it is a pursuit that amuses the fancy and 

 exercises the memory, without improving the mind, 

 or advancing any real knowledge ; and, where the 

 science is carried no farther than a mere systematic 

 classification, the charge is but too true. But the 

 botanist that is desirous of wiping off this aspersion, 

 should be by no means content with a list of names ; 

 he should study plants philosophically, should inves- 

 tigate the laws of vegetation, should examine the 

 powers and virtues of efficacious herbs, should pro- 

 mote their cultivation, and graft the gardener, the 

 planter, and the husbandman on the phytologist. 

 Not that system is by any means to be thrown aside 

 without system the field of Nature would be a path- 

 less wilderness but system should be subservient to, 

 not the main object of, pursuit. 



Vegetation is highly worthy of our attention, and 

 in itself is of the utmost consequence to mankind, 

 and productive of many of the greatest comforts and 



