[1318] MS.:
Till taught to range the wood, or wing the air,
There instinct ends its passion and its care.
[1319] Locke, Civil Government, book ii. chap. vii. sect. 79: "The conjunction between male and female ought to last so long as is necessary to the support of the young ones. And herein, I think, lies the chief, if not the only reason, why the male and female in mankind are tied to a longer conjunction than other creatures, whose young being able to subsist of themselves before the time of procreation returns again, the conjugal bond dissolves of itself."
[1320] Bolingbroke, Fragment 3: "Reason improved sociability, extended it to relations more remote, and united several families into one community, as instinct had united several individuals into one family." "Interest" in Pope's line signifies "advantage." Reason, he says, teaches man to improve on the ties of instinct, and form connections beyond his immediate family, whereby he at once extends his love, and the advantages derived from it.
[1321] That is, man becomes constant from choice.
[1322] MS.:
And ev'ry tender passion takes its turn.
The line in the text alludes to Pope's hypothesis that every virtue is grafted upon a ruling passion.
[1323] "Charity" is used in the antiquated sense of "love." "New needs," says Pope, give rise to "new helps," and the virtue "benevolence" is grafted upon the natural affections.
[1324] He means that the latest brood, being young children, love their parents by nature, while the previous brood, being grown up, only love parents from habit.