Human Nature Essentially Mortal, as Proved By Nature and Revelation, continued

The most powerful natural argument in favour of the popular doctrine has yet to be noticed. It is the one mainly relied upon by all its great advocates. It is this: It is an ascertained fact in physiology that the substance of our bodies undergoes an entire change every seven years - that is, there is a gradual process of substitution going on, by which the atoms one after another, are expelled from the body as their vital qualities are worn out, and their place filled up by new ones from the blood; so that at the end of the period mentioned, the body is made up of entirely new substance. Yet, notwithstanding this constant mutation of the material atoms of the body, and this periodical change of its entire substance, memory and personal identity remain unaffected to the close of life. An old man at eighty feels he is the same person he was at ten, although at eighty he has not a single particle of the matter which composed his body when a boy, and the argument is that the thinking faculty and power of consciousness must be the attribute of some immaterial principle residing in the body, but undergoing no change. Now this has all the appearance of conclusiveness. However, let us look at it narrowly. The question to be considered is - whether this fact of continuous identity amid atomic change, can be explained in accordance with the view which regards the mind as a property of living brain substance. The question is answered by this well known fact, that the qualities resulting from any organic combination of atoms are transmissible to other atoms which may take their place as organic constituents. An atom as it exists in food has no power of sensation; but let it be assimilated by the blood and incorporated with any of the nerves, and it possesses a sensitive power it formerly did not have. It becomes part of the organisation, and feels whether in man or animal. Why? Because it takes up and perpetuates the organic qualities which its predecessor has left behind. On this principle, we find that the mark of a scar will be continued in the flesh through life; and so also with discolourations of the skin, which exist in some persons from congenital causes. This perpetuation of physical disfigurement could not take place if it were not for the fact of the transmissibility of corporate qualities to migratory corporate constituents. Now, if we apply this principle to the brain, we have a complete solution of the apparent difficulty on which the argument of the question is founded. Mind is the result of impressions on the living brain, and personal identity of the sum of those impressions. This definition may be scouted, but it will quietly commend itself to honest reflection. It will not be questioned by the student of human nature, though it may not be understood. Mental impression is a fact, though a mystery, alike in men and animals; and facts are the things that wise men have to deal with. It is impossible to explain, or even to comprehend, the process by which thought is begotten in the tissues of the brain; but that the process takes place will not be denied. We are conscious of the process, and feel the result in the possession of separate individuality - the power of contemplating all other persons and things objectively. Now, in order to perpetuate this result, all that is necessary is to preserve the integrity of the organ evolving it. This, of course, involves the introduction of fresh material into its structure, but it does not imply an invasion of the process going on in it, which the argument in question supposes; the process conquers the material, and converts it to its own uses, and not the material the process. Who ever heard of a man's bone turning to wheat from the eating of flour? The nutritive apparatus assimilates, which is in fact the answer to the argument. The new material entering the brain is assimilated to its existing condition; and thus, although the atoms come and go for a lifetime, the condition remains substantially unaltered, like a fire kept up by fuel. If, then, we are asked how a man at eighty feels himself to be the same person that he was at ten, though his entire substance is changed, we reply, those brain impressions which enable him to feel that he is himself, have been kept up all along, though modified by the circumstances and conditions through which he has passed. The process of change is so slow that the new atoms take on the organic qualities of the old, as they are gradually incorporated with the brain, and sustain the general result of the brain's action in preserving its continuous function unimpaired. If cases could be cited in which identity survived the destruction of the brain, the case would stand differently; but as a fact, it is only to be found in connection with a perpetuated brain organisation.

These are the main "natural" arguments relied upon for proof of the current theological conception of the immortality of the soul. It will be observed that none of them is really logical. Each of them falls through when thoroughly looked into. The natural argument on the other side of the question will be found to stand in a very different position. At the very outset we are confronted with the difficulty of conceiving how immateriality can inhere in a material organisation. Cohesion and conglomeration require affinity as their first condition, but, in this case, affinity is entirely wanting. What connection can exist between "matter" and the immaterial principle of popular belief? They are not in the nature of things susceptible of combination. Yet in the face of this difficulty, we find that the mind is located in the body. It is not a loose ethereal thing, capable of detachment from the material person. It is inexorably fixed in the bodily framework, and never leaves it while life continues. If we enquire in what portion of the body it is specially located, we instinctively answer that it is not located in the hand, nor in the foot, nor in the stomach, nor in the heart, nor in any part of the trunk. Our consciousness unerringly tells us that it is in the head. We feel as a matter of experience, whatever our theory may be, that the mind cohabits with the substance of the brain.

Extending our observation externally, we never discover mind without a corresponding development of brain. Deficient brain is always found to manifest deficient reason, and vice versa. Master minds in science and literature have larger and deeply convoluted cerebrums. If the popular theory were correct, mind ought to be exhibited independently of either quantity or quality of organisation.

Again, if the mind were immaterial, its functions would be unaffected by the conditions of the body. Thinking and feeling would never abate in vigour or vivacity. We should always be serene and clearheaded - always ready for the "study," whatever might be the state of the bodily machinery; whereas we know that the opposite is the case. Sickness or overwork will exhaust the mental energies, and make the mind a blank. Languor and dullness of spirits are of common experience. We can all testify to days of ennui, in which the mind has refused to perform its office; and we can remember, too, the uneasy pillow when horrible visions have scared us. This never happens in a good state of health, but always when the material organisation is out of order. How is this? Does it not tell against the theory which represents the mind as an immaterial, incorruptible, imperishable thing? The mind is the offspring of the brain, and is therefore affected by all its passing disorders.