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CHAPTER XVIII.

INSTINCTS.

THE order may not be very obvious, by which I place inflincts next to relations. But I confider them as a species of relation. They 'contribute, along with the animal organization, to a joint effect, in which view they are related to that organization. In many cafes they refer from one animal to another animal; and, when this is the cafe, become strictly relations in a second point of view.

An INSTINCT is a propenfity, prior to experience, and independent of instruction. We contend, that it is by inftinct that the fexes of animals feek each other; that animals cherish their offspring; that the young quadruped is directed to the teat of its dam; that birds build their nefts, and brood with fo much patience upon their eggs; that infects, which do not fit upon their eggs, depofit them in those particular fituations, in which the young, when hatched, find their appropriate food; that it is inftinct, which carries the

falmon,

falmon, and fome other fish, out of the fea into rivers, for the purpose of shedding their fpawn in fresh water.

We may felect out of this catalogue the incubation of eggs. I entertain no doubt, but that a couple of fparrows hatched in an oven, and kept separate from the rest of their species, would proceed as other fparrows do, in every office which related to the production and prefervation of their brood. Affuming this fact, the thing is inexplicable upon any other hypothefis, than that of an instinct, impreffed upon the conftitution of the animal. For, first, what should induce the female bird to prepare a neft before she lays her eggs? It is in vain to suppose her to be poffeffed of the faculty of reasoning; for no reasoning will reach the cafe. The fullness or diftenfion which she might feel in a particular part of her body, from the growth and folidity of the egg within her, could not poffibly inform her, that she was about to produce fomething, which, when produced, was to be preserved and taken care of. Prior to experience, there was nothing to lead to this inference, or to this fufpicion. The analogy was all against it;

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for, in every other inftance, what iffued from the body was caft out and rejected.

But, fecondly, let us fuppofe the egg to be produced into day: How should birds know that their eggs contain their young? There is nothing either in the afpect, or in the internal compofition of an egg, which could lead even the most daring imagination to a conjecture, that it was hereafter to turn out, from under its thell, a living perfect bird. The form of the egg bears not the rudiments of a refemblance to that of the bird. Infpecting its contents, we find fill lefs 'reafon, if poffible, to look for the refult which actually takes place. If we should go fo far, as, from the appearance of order and diftinction in the difpofition of the liquid fubftances which we noticed in the egg, to guefs that it might be defigned for the abode and nutriment of an animal, (which would be a very bold hypothefis,) we should expect a tadpole dabbling in the flime, much rather than a dry, winged, feathered creature; a compound of parts and properties impoffible to be used in a state of confinement in the egg, and bearing no conceivable relation, either in quality or material, to any thing obferved in

it. From the white of an egg, would any one look for the feather of a goldfinch? or expect from a fimple uniform mucilage, the moft complicated of all machines, the most diverfified of all collections of fubftances? Nor would the process of incubation, for fome time at leaft, lead us to fufpect the event. Who that faw red ftreaks, fhooting in the fine membrane which divides the white from the yolk, would fuppofe that thefe, were about to become bones and limbs? Who, that efpied two difcoloured points firft making their ap pearance in the cicatrix, would have had the courage to predict, that these points were to grow into the heart and head of a bird? It is difficult to ftrip the mind of its experience. It is difficult to refufcitate furprife, when familiarity has once laid the fentiment aileep. But could we forget all that we know, and which our fparrows never knew, about oviparous generation; could we diveft ourselves of every information, but what we derived from reafoning upon the appearances or quality difcovered in the objects presented to us, I am convinced that Harle quin coming out of an egg upon the ftage, is not more aftonishing to a child, than the hatching

Y 4

hatching of a chicken both would be, and ought to be, to a philofopher.

But admit the fparrow by fome means to know, that within that egg was concealed the principle of a future bird, from what chymift was fhe to learn, that warmth was necessary to bring it to maturity, or that the degree of warmth, imparted by the temperature of her own body, was the degree required?

To fuppofe, therefore, that the female bird acts in this process from a fagacity and reason of her own, is to suppose her to arrive at conclufions, which there are no premises to jus tify. If our sparrow, fitting upon her eggs, expect young fparrows to come out of them, the forms, I will venture to fay, a wild and extravagant expectation, in oppofition to prefent appearances, and to probability. She muft have penetrated into the order of nature, further than any faculties of ours will carry us and it hath been well obferved, that this deep fagacity; if it be fagacity, fubfifts in conjunction with great ftupidity, even in relation to the fame fubject. "A chymical operation," fays Addifon, could not be followed with greater art or diligence, than is feen in hatching a chicken: yet is the procefs carried on

without

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