We have been accustomed, and properly, to regard the nervous system, or that portion of it which is connected with animal life--that which renders us conscious of surrounding objects and susceptible of pleasure and of pain--as the source of intellectual power and moral feeling. It is so with ourselves. All our knowledge is derived from our perception of things around as. A certain impression is made on the outward fibres of a sensitive nerve. That impression, in some mysterious way, is conveyed to the brain; and there it is received--registered--stored--and compared; there its connections are traced and its consequences appreciated; and thence a variety of interesting impressions are conveyed, and due use is made of them. THE SENSE OF SMELL Our subject--the intellectual and moral feelings of brutes, and the mechanism on which they depend--may be divided into two parts, the portion that receives and conveys, and that which stores up and compares and uses the impression. The portion that receives and conveys is far more developed in the brute than in the human being. Whatever sense we take, we clearly perceive the triumph of animal power. The olfactory nerve in the horse, the dog, the ox, and the swine, is the largest of all the cerebral nerves, and has much greater comparative bulk in the quadruped than in the human being. The sense of smell, bearing proportion to the nerve on which it depends, is yet more acute. In man it is connected with pleasure--in the inferior animals with life. The relative size of the nerve bears an invariable proportion to the necessity of an acute sense of smell in the various animals--large in the horse compared with the olfactory nerve in the human being--larger in the ox, who is often sent into the fields to shift for himself--larger still in the swine, whose food is buried under the soil, or deeply immersed in the filth or refuse,--and still larger in the dog, the acuteness of whose scent is so connected with our pleasure.