For, let us remember, it is only in a certain sense that the eye sees, or the ear hears; in the former instance, nothing more than an image of objects is inversely reflected on the retina, and yet the mind recognises these objects in their proper position; and what is more, not double, though the same object is figured on the retina of each eye, or, in the case of insects, on the retina of scores of eyes. In hearing, the minute auditory nerves merely receive an impulse from the vibrations or wavelets of the elastic atmosphere, and this constitutes what we call noise, tones, music, voice. But these tones or noises are in the mind only; they are not appreciated by the exercise of any other sense.
Having thus briefly endeavoured to show the harmony of the general order of nature, as far as our globe and its animal and vegetable forms are concerned, we shall proceed to the consideration of another portion of our subject, and commence with it a fresh chapter.
[CHAPTER II.]
MAN'S KNOWLEDGE OF THE QUALITIES OF MATTER OBTAINED THROUGH THE MEDIUM OF THE SENSES.
If we reflect upon man, beginning with the savage, and ending with the philosopher, we shall find, that although the mental difference, or rather the extent of acquired knowledge possessed by each respectively, is very great, that the little the one possesses, and all that the other may boast of, are based upon certain simple principles, seized upon by the mind through the medium of the senses, and made more or less the subjects of consideration and research.
If the philosopher can display a mass of knowledge of which the savage is ignorant, the savage can show to the philosopher that his mind in some things is more ignorant than his own. Both have used their senses; both have examined and reflected; both have accumulated a store of information, which they turn to account: but the savage cares only for that which enables him to enjoy animal existence. He, therefore, investigates the habits of the animals around him, and the nature of the plants; he tames some of the former, he cultivates some of the latter; he stores up provisions, he invents rude weapons; he builds kraals, or huts; he fashions boats, kajaks, or proas; he employs fire; and though he cannot discuss the laws of caloric, he knows many of them practically. In fact, his senses are to him the inlets of ideas, without any abstruse cogitation. He cannot but acquire knowledge through his senses, but he labours to acquire no more than is subservient to his present interest. To the philosopher, the senses are also the inlets of ideas; but then he is thereby led to abstruse cogitation, to experiments, and reiterations upon these, forming theories to be rejected or adopted, as laborious investigation may determine.
And wherefore?—Not contented with the vacuity of mere animal enjoyments, he antedates his spiritual existence, and while yet on earth soars to other worlds, or dives into the profound mysteries of nature. Between the rude savage and the philosopher there are innumerable gradations; yet the rude savage, if cultivated, might become the philosopher—and why?—Because, though mental powers, like bodily powers, differ, the mental anatomy, like the corporeal, is on the same plan; and, figuratively speaking, the muscles of the former may become by exercise as developed as the muscles of the latter. To what fields, then, of knowledge are the senses avenues—and avenues, because they are adapted to the condition of the globe we inhabit, and because the impressions which they receive are seized upon by the mind, being there alone made palpable; and because the mind, by a reflex action, thence derives ideas, and combines and analyzes them.
The higher animals possess the same senses as man; and, it may be asked, Why do they not gain a similar knowledge to that which man acquires? We have already said, that the higher animals possess something which cannot but be termed mind, since they have passions and affections, memory, etc., which are qualities of mind, and not of matter. But, then, their mind is not only inferior in degree to that of man, but different in its anatomical construction. Certain animals, moreover, are inferior to others, and among animals of the same species there are different degrees of mental as well as of bodily force. Here, however, we can only generalize. Let it suffice, then, that we adduce for the purpose of illustration an animal with which we are all familiar—a domesticated animal, capable of a high degree of education, and which man has trained to the most various and opposite purposes—we allude to that attached servant of our race, the dog. Let it stand as a type of the higher quadrupeds.
That the dog remembers, and even to a certain extent reasons, cannot, we think, be contradicted. A shepherd's dog not only obeys its master's directions, but of its own accord will keep the sheep together, prevent them from wandering out of the right track, search for them when buried in the snow, watch over them at night, and defend them against the incursions of the wolf. The sportsman's dog, when he sees his master take down his fowling-piece, examine the locks, and equip himself for the field, is quite aware of the result of these proceedings, and manifests unequivocal symptoms of pleasure. Dogs, moreover, may be taught to beg, to fetch and carry, to feign themselves dead, and continue motionless until the word of command be given, and to take their part in a scenic representation. There are, indeed, numerous authentic instances on record of dogs having acted with astonishing sagacity, and which prove not only memory, but a train of reasoning carried out with singular precision. In such instances, we cannot say that the animals are instinct-directed, because the actions performed are out of the common course of events, and are only occasional; every dog, under the same circumstances, would not act in anything like the same manner.