perceive that it is gorged with insects, in every progressive stage of dissolution and of assimilation to the solid and fluid matter of the animal. We need not doubt, then, that the acrid chemical agent, which is accomplishing this conversion of the substance of one animal into that of another, acts also, when not so occupied, in some such way upon the sack itself as to excite an uneasiness, which being conveyed to the centre of consciousness, and being there conjoined with familiar impressions from the external world, and meeting there, also, the springs of muscular irritability, give impulse to the machine in the direction towards that external object, the image of which already exists in the memory conjoined with the sensations of gratified appetite. Now, in this dissection of the machine of animal life, the relation of parts, and their interaction for the production of a single result, are perfectly intelligible;-as much so as is the mechanism of a watch. But in the construction both of the watch and of the bird, there are certain ultimate connexions which lie beyond our ken, and which can be known only in their products. In the watch, these inscrutable facts are-the principle of elasticity in the springs, and the vis inertia of the balance-wheel. That is to say, the two last causes in the machine can be traced no further than to a certain expansive property of steel, and to the universal law of momentum. In the machinery of the bird, the unknown or ultimate facts, though more in number, are not in themselves more recondite or obscure; but just as much soneither more nor less. They are such as these; the chemical power of the several fluids; the

principle of muscular contraction; the principle of assimilation and growth; and the whole cerebral apparatus of sensation, and the interaction of sensations from without and within, producing locomotion, or muscular action. That is to say, as in the watch, so in the bird, the arrangement of parts and functions is intelligible, but the powers are unknown.

And yet, notwithstanding our hopeless ignorance, in both instances, of the ultimate connexions, we may safely and certainly reason concerning the proximate and intelligible parts of the contrivance; and may, without being supposed to understand what in all cases lies beyond human knowledge, affirm that we comprehend the mechanism both of the watch and of the bird. The theory of the regular movement of wheels and indicators is truly given when all the parts that connect the elasticity of the two springs with the vis inertia of the balance-wheel are described. And in like manner, the theory of action in the animal is truly given, when the several correspondences between the stomach, wings, eyes, ears, and brain of the bird, are enumerated.

But this one account of the movements of the animal machine does not explain all the facts observable in the wanton flight of a swallow; for, beside some other movements, which, like those already mentioned, are easily traced home to certain functions or organs, as those were traced to the stomach, there are actions not to be in any such manner explained. It by no means appears that the little unlicensed venator invariably directs his flight towards the nearest or the best-fed gnat at any moment

within his circle of vision; nor that he is diverted from the pursuit of his victim, only by this or that assignable object of alarm, or of social attraction: his aerial gambols are too various, free, and erratic, to be all assigned to impulses of this order. It may be well, however, to turn to another subject in search of this other law of animal agency.

The young horse that, free a-field, makes large orbits over the level mead, is neither hunting his prey, nor flying before an enemy; yet does he put forth his powers of speed as if death were behind him, or life before. He stops on his course; snuffs the gale; leaps and plunges; snorts, and again darts onward;-in pursuit of nothing! Here our consciousness (unless octogenarians) aids us to interpret the seemingly causeless activity. To the plenitude of muscular power, and to the full tide of animal spirits, belongs an appetite asking for movement and sport; and this same desire, combined with other impulses, or taking its turn with them, in colts, kittens, children, and boyish adults, is the cause of a great part of all the hurry and the change which keep the world from stagnation.-But again; if the gay activity of the young horse be narrowly observed, a belief will be suggested that his course from side to side of his pasture-his capricious pauses, and his starts, obey yet some other internal law. He bites the grass a moment,-raises his head,seems to ponder some freakish device, and, like the lightning, springs from his place, and is hardly to be followed by the eye. May it not be surmised-and if the manners of animals of all classes are watched, must it not be be

lieved, that within the brain of the animal, (if indeed the brain be the seat of consciousness) as well as within the brains of men, an incessant movement is going on;* or a stream of recollected sensations, fortuitously connected one with another, is flowing perpetually? Then these recovered emotions, or sensations, meeting, each moment, either with impressions from the senses, or with desires from the several viscera of life, form infinitely varied combinations of action. It is as if this under-current of thought had been included in the mental structure of the animal for the very purpose of breaking up that uniform, and mechanical, and calculable succession of movements, which must needs have resulted from the dull influence of three or four simply reasonable motives of action. By the means of this exquisite contrivance, which diversifies, indefinitely, the agency of the animal-the animal moves over a far larger circle of activity-meets with a thousand times more new occasions, and comes in contact with many more means of enjoyment, than could happen, if he were the mere creature of his appetites and desires.

In reference to these primary causes of action, namely, the desires of animal life, and the irascible, amatory, and cautionary emotions that spring from them; and the love of muscular action; and the suggestions of the perpetual current of thought; it is to be noted, that muscular movement takes place, in the strictest sense, spontaneously; or, shall we say, simultaneously with its cause? The cause and effect

See note U.

are not divided by an interval of deliberation; there is no "determining to determine," nor willing to will," nor balancing of reasons. To such instances the metaphysical analysis of volition, as consisting of a series of mental operations, is utterly inapplicable. We derive the notion of such an analysis from a class of volitions essentially differing from animal agency; and it is a gross violation of the rules of science to extend it to cases with which it has no affinity.

But the lower classes of the sentient system offer also to our observation (in its ruder forms, at least) that complex order of volitions which, in the adult and cultured human subject, often supersedes those of a simple and elementary kind. Let us turn from the young horse a-field, to the old horse in the stable; and we shall find, in his behaviour, many instances of an agency which implies a mental process of inference; or, the connecting of event with event, and the deduction of a motive therefrom: or, in other words, we shall find him reasoning to a certain extent; and acting in a manner which could never be accounted for on any of the principles already mentioned. The hackney who, times innumerable, has been saddled or collared, when he catches the footstep of his groom approaching the stable, awakes from the lethargy in which perhaps he had been standing in front of his rack: and if this lord of his destinies appears booted and spurred, and lays a hand upon the saddle and bridle, the provident animal, not doubting that he is to be led from his stall, to which he may not soon return, begins, without loss of time, and with the utmost