wisdom in all others shows that they are endowed with a mental principle essentially of a different nature from that of the human race. "They do many things even better than ourselves," says Descartes; "but this does not prove them to be endowed with reason, for this would prove them to have more reason than we have, and that they should excel us in all other things also"; for reason can act not only in one direction, but in all.
But it will be said that instinct is not invariable,—that it often displays a capacity of accommodating itself, like reason, to circumstances, and is therefore a principle the same in kind with it,—or else that the animal has something of the rational faculty superadded to the instinctive. But does the animal make these variations in its conduct from a true perception of their meaning and purpose?
It is very natural for us to ascribe to reason those actions of other animals which would be ascribable to reason, if performed by man. "If," says Keller, (an old German writer,) "the fly be enabled to choose the place which suits her best for the deposition of her eggs, (as, for instance, in my sugar-basin, in which I placed a quantity of decaying wheat,) she takes a correct survey of every part and selects that in which she believes her ova will be the best preserved and her young ones well cared for." The fly, in this instance, apparently exercises an intelligent choice; but does any one doubt that the selection she makes is determined wholly by a blind, uncalculating instinct? The beaver selects a site for his dam at a place where the depth, width, and rapidity of the stream are most fit. There is a tree upon the bank, and food and materials for his work in the vicinity. If a man should attempt to build a beaver's dam, he would abstractly consider all these elements of fitness. The outward manifestations of the quality of abstraction are equally observable in either case. But we must not hastily conclude, because the beaver in one instance acts in a manner apparently reasonable, that he has any reason of his own; for, when we come to study the habits of this animal, we find that he displays all the characteristics of the instinctive principle. If animals are endowed with instincts which apparently act so much like reason in the ordinary course of their operations, we should not at once conclude that there is any need of endowing them with a modicum of reason to account for their deviations from this course, which do not outwardly resemble the acts of reason any more strongly. And besides, it is said, that, if we refer the variations to an intelligent principle, we must refer the ordinary conduct to the same principle. To use an old illustration,—if a bird is reasonable and intelligent, when, on perceiving the swollen waters of the stream approach her half-finished nest, she builds higher up the bank, she was intelligent while making her first nest, and was always intelligent; for how otherwise, it is asked, could she know when to lay down instinct and take up reason?
Instinct aims at certain definite ends; but these ends cannot always be reached by the same means, especially when places and circumstances are not the same. Accommodation is necessary, or it could not always produce the effects for which it is intended. Would the instinct of the spider be complete, if, after it has guided her to spin a web so neat and trim and regular, it did not also lead her to repair her broken snare, when the cords have been sundered by the struggles of some powerful captive? But this pliancy of the spider's instinct is no more remarkable than the contingent operation of the instincts of many species of animals. "It is remarkable," says Kirby, "that many of the insects which are occasionally observed to emigrate are not usually social animals, but seem to congregate, like swallows, merely for the purpose of emigration." When certain rare emergencies occur, which render it necessary for the insects to migrate, a contingent instinct develops itself, and renders an unsocial species gregarious.
It is probable that most of our domesticated species, exhibiting as they do in that condition attainments foreign to their natural habits and faculties in a wild state, were endowed with provisional instincts with a view to their association with man. But generally the docility of animals does not extend to attainments which are radically different from their habits and faculties in a wild state. Casual acquirements, which have no relation to their exigencies in their natural condition, never become hereditary, and are not, therefore, instinctive. A young pointer-dog, which has never been in the fields before, will not only point at a covey of partridges, but will remain motionless, like a well-trained dog. The fact that the sagacity of the pointer is hereditary shows that it is the development of an instinctive propensity; for simple knowledge is not transmitted by blood from one generation to another. We have heard of a pig that pointed game, and of another that was learned in letters; but we ascertain in every such instance that their foreign acquirements do not reappear in their progeny, but end with the pupils of the time being. The pig's peculiarity of pointing did not arise from the development of a provisional instinct, because it does not become hereditary; but the same act in the pointer-dog is instinctive,—for, when once brought out by associating with man, it has remained with the breed, being a part of the animal's nature, which existed in embryo till it was developed by a companionship with man, for whose use this faculty was alone intended.
Although the animals which especially display these exceptional or contingent instincts are those which are fitted for the use and comfort of man and may be domesticated, it is doubtless true that many other species are in some degree provided with them, and that they thus have a plasticity in their nature which enables them to exercise, under particular circumstances, unlooked-for attention, foresight, and caution. And besides, it is only in analogy with the laws of the physical world that instinct should admit of a slightly diversified application.
It is to be noticed in this connection that many animals are gifted with a wonderful sensibility of the senses,—the action of which is sometimes mistaken not only for the action of instinct, but for that of reason also. The acuteness of the sense of smell in the dog, which enables him to trace the steps of his master for miles through crowded streets by the infinitesimal odor which his footsteps left upon the pavement, is quite beyond our conception. Equally incomprehensible to us are the keenness of sight and wide range of vision of the eagle, which enable him to discover the rabbit nipping the clover amid the thick grass at a distance at which a like object would be to us altogether imperceptible. The chameleon is enabled to seize the little insects upon which it feeds by darting forth its wonderfully constructed tongue with such rapidity and with such delicacy of perception that "wonder-loving sages" have told us that it feeds upon the air.
It has been the belief of some observers that some animals have senses by which they are enabled to take cognizance of things which are not revealed directly to our senses. It is easy enough to conceive of beings endowed with a more perfect perception of the external world, both in its condition and the number of objects it presents, than we have, by means of other organs of outward perception. Voltaire, in one of his philosophical romances, represents an inhabitant of one of the planets of the Dog-Star as inquiring of the Secretary of the Academy of Sciences in the planet of Saturn, at which he had recently arrived in a journey through the heavens, how many senses the men of his globe had; and when the Academician answered, that they had seventy-two, and were every day complaining of the smallness of the number, he of the Dog-Star replied, that in his globe they had very near one thousand senses, and yet with all these they felt continually a sort of listless inquietude and vague desire which told them how very imperfect they were. But we shall not travel so far as this for our illustrations. We have all seen in the fields and about our houses birds and insects which seem to take cognizance of the electric state of the atmosphere; and we have learnt to feel quite sure, when, early in the morning of a summer's day, we see fresh piles of sand around the holes of the ants, that a storm is approaching, although the sky may as yet be cloudless and the air perfectly serene. In like manner birds perceive the approach of rain, and are all busy oiling and smoothing their feathers in preparation for it; and then, before the clouds break away, they come out from their retreats and joyfully hail the return of fair weather. So, by some analogous sense, the birds of passage are informed of the approach of winter and the return of spring.
It is doubtless true that in some animals the senses are immediately connected with instincts which assist and extend their operation. Metaphysicians and physiologists are agreed that the perception of distance is an acquired knowledge. The sense of sight by itself principally makes us conversant with extension only. The painting upon the retina of the eye presents all external things with flat surfaces and at
