176 
INSTINCTS. 
the sparrow tribe, when it is perceived that the young 
brood can fly and shift for themselves, then the parents 
forsake them forever; and though they continue to live 
together, pay them no more attention than they do to other 
birds in the same flock.* I believe the same thing is true 
of all gregarious quadrupeds. 
In this part of the case, the variety of resources, expedi¬ 
ents, and materials, which animals of the same species are 
said to have recourse to, under different circumstances, and 
when differently supplied, makes nothing against the doc¬ 
trine of instincts. The thing which we want to account 
for, is the propensity. The propensity being there, it is 
probable enough that it may put the animal upon different 
actions, according to different exigencies. And this adap¬ 
tation of resources may look like the effect of art and con¬ 
sideration, rather than of instinct; but still the propensity is 
instinctive. For instance, suppose what is related of the 
woodpecker to be true, that, in Europe, she deposits her 
eggs in cavities, which she scoops out in the trunks of soft 
or decayed trees, and in which cavities the eggs lie con¬ 
cealed from the eye, and in some sort safe from the hand 
of man; but that, in the forests of Guinea and the Brazils, 
which man seldom frequents, the same bird hangs her 
nest to the twigs of tall trees; thereby placing them out of 
the reach of monkeys and snakes; i. e. that in each situa¬ 
tion she prepares against the danger which she has most 
occasion to apprehend: suppose, I say, this to be true, and 
to be alleged, on the part of the bird that builds these nests, 
as evidence of a reasoning and distinguishing precaution, 
still the question returns, whence the propensity to build 
at all? 
Nor does parental affection accompany generation by any 
universal law of animal organization, if such a thing were 
intelligible. Some animals cherish their progeny with the 
most ardent fondness, and the most assiduous attention; 
others entirely neglect them; and this distinction always 
meets the constitution of the young animal, with respect 
to its wants and capacities. In many, the parental care 
extends to the young animal; in others, as in all oviparous 
fish, it is confined to the egg, and even, as to that, to the 
disposal of it in its proper element. Also, as there is 
generation without parental affection, so is there parental 
instinct, or what exactly resembles it, without generation. 
In the bee tribe, the grub is nurtured neither by the father 
* Goldsmith’s Nat. Hist. vol. iv. p. 244 . 
