6. _Muscular sense._--God in his infinite wisdom has constructed all living things, and no doubt there is much yet for the philosopher to discover in the organization of animal bodies; there is, moreover, something that he never will understand, namely, life intrinsically considered, and the manner in which the immortal spirit and the dying body communicate with and influence each other. But though these points must ever remain a mystery, still there are those the obscurity of which science has to a certain degree dispelled, and it was reserved for a late scientific anatomist to prove to the world, that the nerves of sensation and the nerves of motion are essentially distinct, although interblended together they pervade every muscle. Hence, as this philosopher observes, (we mean sir Charles Bell,) we are sensible of the action of our muscles, because these muscles have two classes of nerves; and he found that in exciting one of these the muscle contracted, while on exciting the other no action took place. The nerve which had no power to make the muscle contract was the nerve of sensation. Continuing his experiments, he proved that there is a nervous circle connecting the muscles with the brain, that one nerve is not capable of transmitting what is called the nervous spirits in two different directions at one instant of time, but that for the regulation of muscular action there is a nerve of sensibility, to convey a sensation of the condition of the muscles to the sensorium, as well as a nerve of motion for conveying the mandate of the will to the muscles. He also demonstrated, that in their distribution through the body, the nerves which possess these two distinct powers of conveying sensation, and of exciting the muscles to contraction, are wrapped up, or, as it were, woven together in the same sheath, and that they present to the eye the single appearance of one nerve. It was only by examining the nerves at their roots, that is, where they arise from different tracts of the brain and spinal marrow, and before they coalesce, that this philosophic anatomist succeeded in demonstrating their distinct functions. In the face, the nerve of motion passes by a circuitous route, apart from the nerve of sensation, to be distributed to the muscles; and, therefore, the distinct characters of these two nerves were, as sir C. Bell asserts, more easily proved by experiment than in any other part of the body. The nerves of sensation then feel, or rather recognise, those actions of the muscles which are excited through the medium of the nerves of contraction, and these nerves of contraction, as far as the voluntary muscles are concerned, obey the commands of an immaterial being--mind, spirit, soul; in the lower animals, so far as we know, this principle is transient, for they have no ideas of life, or of death, or of futurity; but in man, the soul is immortal, and for the future bliss of this immortal essence revelation affords a certain guide.