OF SELBORNE. 
231 
would be deftitute and forfaken. But the parent birds feem to 
maintain a jealous fuperiority, and to oblige the young to feek for 
new abodes : and the rivalry of the males, in many kinds, prevents 
their crowding the one on the other. Whether the fwallows and 
houfe-martins return in the fame exadl number annually is not eafy 
to fay, for reafons given above : but it is apparent, as I have re- 
marked before in my Monographies, that the numbers returning 
bear no manner of proportion to the numbers retiring. 
LETTER XL. 
TO THE SAME. 
DEAR SIR, Seleorne, June 2, i77g. 
The Handing objcdllon to botany has always been, that it is a 
purfuit that amufes the fancy and exercifes the memory, with- 
out improving the mind or advancing any real knowledge : and, 
where the fcience is carried no farther than a mere fyftematic 
claffification, the charge is but too true. But the botanift that is 
defirous of wiping off this afperfion ihould be by no means con- 
tent with a lift of names ; he fliould ftudy plants philofophically, 
fliould inveftigatc the laws of vegetation, ihould examine the 
powers and virtues of efiicacious herbs, fliould promote then- 
cultivation ; 
