OF SELBORNE. 247 



Ever since I have attended to the subject of ornithology, 

 I have always supposed that that sudden reverse of affection, 

 that strange avrurTopyy which immediately succeeds in the 

 feathered kind to the most passionate fondness, is the occa- 

 sion of an equal dispersion of birds over the face of the 

 earth. Without this provision, one favourite district would 

 be crowded with inhabitants, while others would be desti- 

 tute and forsaken. But the parent birds seem to maintain 

 a jealous superiority, and to oblige the 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 rea- 

 sons given above ; but it is apparent, as I have remarked 

 before in my Monographies, that the numbers returning 

 bear no manner of proportion to the numbers retiring. 



LETTER XL. 



TO THE HONOURABLE DAlNES BARRINGTOX. 



SELBORNE, June 2, 1778. 

 standing objection to botany has always 

 been, that it is a pursuit that amuses the 

 fancy and exercises the memory, without im- 

 proving 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 npmes; he should study plants philosophically, should 

 investigate the laws of vegetation, should examine the 

 powers and virtues of efficacious herbs, should promote 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 



