220 NATURAL HtSTOltY OF SELBORNE. 



spring which pairs shall visit us, and reoccupy their ancient 

 haunts ? 



Ever since I have attended to the subject of ornithology, 

 I have always supposed that that sudden reverse of affec- 

 tion, that strange avTca-Topyrj, which immediately succeeds 

 in the feathered kind to the most passionate fondness, is the 

 occasion 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 

 prevent 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 Monographies, that the numbers returning bear no 

 manner of proportion to the numbers retiring. 



LETTER XL. 



Selbohne, June 2nd, 1778. 



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 know- 

 ledge ; and, where the science is carried no further 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 investigate the 



