_These Facts do not prove Reason._--Facts of this nature, however interesting, and well authenticated, must be regarded rather as exceptions to the ordinary rule, the nearest approach which mere instinct has been known to make toward the dividing line that separates the brute from the human intelligence. They do not, in themselves, prove the existence of reason, of a discriminating and reflecting intelligence, on the part of the animal; for the same law of nature that impels the creature to build its nest or its comb, under ordinary circumstances, in the ordinary manner, may certainly be supposed to be capable of inducing a change of operation to meet a sudden exigency, and one liable at any time to occur. It is certainly not more wonderful, nor so wonderful, that the bee should be induced to brace her comb, or the spider her web, when in danger, as that either should be able to construct her edifice originally, at the precise angle employed. It must be remembered, moreover, that, in the great majority of cases, brute instinct shows no such capacity of adaptation to circumstances. _The Question before us._--We are ready now to inquire how far that which we call instinct in the brute, differs from that which we call intelligence in man. Is it a difference in _kind_, or only in _degree_? A glance at the history of the doctrine may aid us here. _Early Views._--From Aristotle to Descartes, philosophers took the latter view. They ascribed to the brute a degree of reason, such as would be requisite in man, were he to do the same things, and proceeding on this principle, they attributed to animals an intelligence proportioned to the wants of their nature and organization. This principle, it need hardly be said, is an assumption. It is not certain that the same action proceeds from the same principle in man, and in the brute; that whatever indicates and involves intelligence and reason, in the one case, as its source, involves the same in the other. This is a virtual _petitio principii_. It assumes the very point in question. It may be that what man does by virtue of an intelligent, reflecting, rational soul, looking before and after, the brute does by virtue of entirely a different principle, a mere unintelligent impulse of his nature, a blind sensation, prompting him to a given course. This is the question to be settled, the thing to be proved or disproved. And if the view already given of the character of brute instinct, is correct, the position now stated as possible, may be regarded as virtually established.