Büchner. “And yet what Fischer denies is undoubtedly the fact. The nerves themselves do not perceive; they merely call forth sensations by conducting the impressions received to the brain. We do not feel pain in the place injured, but in the brain. If a nerve of sensation be divided in its course to the brain, all the parts which are supplied by it lose their sensibility, for no other reason than that the conducting of the impression to the brain is no longer possible. Every man who has no knowledge of physiological processes believes the feeling of hunger to be in the stomach. This is not so; the brain alone makes us conscious of the feeling. If the nerve uniting brain and stomach be divided, hunger is at an end, nor does it return. Neither does anger arise in the liver, or courage in the chest, but in the brain only” (pp. 143, 144). “Habit and external appearance have led to the false notion that we feel in places subjected to external irritation. Physiology calls this relation ‘the law of eccentric phenomena.’ According to it, we falsely attribute the feeling perceived in the brain to the place where the impression is made.... Persons who have lost their arms or legs by amputation often feel during their whole lives, in atmospheric changes, pains in limbs which they no longer possess. If all his limbs were removed, man would still feel them. From these facts it can scarcely be doubted that there must exist in the brain a topography by means of which the various sensations of the different parts of the body arise. [pg 177] Every part of the body which can be separately perceived must have a corresponding spot in the brain which in some degree represents it in the forum of consciousness” (pp. 144, 145).

Reader. This answer, doctor, is not altogether satisfactory. “The nerves,” of course, “do not perceive.” This I willingly admit; but neither does the brain perceive; for it is the soul that perceives. The nerves “merely call forth sensations by conducting the impressions received to the brain.” This cannot be denied; but it does not prove the non-existence of the soul in the nervous system. Suppose that a pin or a thorn presses the finger; before the impression can be transmitted from the finger to the brain, its reception in the finger must give rise to a change of relation between the soul and the finger itself; which would be impossible, if the soul were not in the finger. For, if the soul is not in the finger, the impression made by the thorn will consist of a merely mechanical movement; and when this movement is communicated to the brain, what sensation can be called forth? A sensation of pain? No; for mere mechanical movement cannot produce a sense of pain, unless it is felt to disagree with the living organism. Now, the pricking is not felt to disagree with the brain, but with the finger. It is therefore in the finger and not in the brain that we feel the pain; which shows that the soul really is in the finger, and in every other part of the body in which we may experience any sensation.

Your reason for pretending that “we do not feel pain in the place injured, but in the brain,” is quite unsatisfactory. It is true that if a nerve of sensation be divided in its course to the brain, all the parts which are supplied by it lose their sensibility; but what of that? Those parts lose their sensibility because they lose their sensitiveness; that is, because the cutting of the nerve, by impairing the body, causes the soul to abandon the organic parts supplied by that nerve. You argue that, if the soul is not present in a given part of the body, when the nerve has been injured, the soul was not present in that same part before the nerve was injured. This inference is evidently wrong. The soul informs the organism, and any part of it, as long as the organs are suitably disposed for the vital operations, and abandons the organism, or any part of it, as soon as the organs have become unfit for the vital operations. Hence, as you cannot infer the non-existence of the soul in the brain of a living man from the non-existence of the same in the brain of a corpse, so you cannot infer its non-existence in a part of the body before the cutting of the nerve from its non-existence in the same part after the nerve has been cut.

The feeling of hunger, you say, is not in the stomach, because “if the nerve uniting brain and stomach be divided, hunger is at an end.” Is not this very curious? Men need none of your theories to know where they feel hungry; and they not only believe, as you say, but also experience, that their feeling of hunger is in the stomach. How can this be reconciled with your theory? You try to discredit the common belief by observing that we “have no knowledge of physiological processes.” This, however, is not true; for although we may not possess your speculative knowledge of those processes, yet we have an experimental knowledge of them, [pg 178] which beats all your speculations. The simplest common sense teaches that a theory contradicted by facts is worth nothing. Now, the fact is that we experience the sensation of hunger in the stomach, and not in the brain; and therefore no physiological theory that contradicts such a fact can be of any value.

You pretend that “habit and external appearance have led to the false notion that we feel in places subjected to external irritation.” This assertion cannot be justified. Habits are acquired by repeated acts; and to assume that habit leads us to a false notion is to assume that we are cheated by our actual sensations; which is inadmissible. As to “external appearances,” it is evident that they have nothing to do with the question, as sensations are not external appearances, but internal realities. Hence when we say that “we feel in places subjected to external irritation,” we express a real fact of which we have experimental evidence, and in regard to which no habit or external appearance can make us err.

The fact that “persons who have lost their arms or legs by amputation often feel during their whole life, in atmospheric changes, pains in limbs which they no longer possess,” does not tend to prove that the brain is the exclusive seat of the soul. Hence I dismiss it altogether. With regard to your conclusion that “every part of the body which can be separately perceived must have a corresponding spot in the brain which in some degree represents it in the forum of consciousness,” I have not the least objection against it; I merely add that no part of the body in which the soul is not actually present can be represented in the forum of consciousness. For if the soul is not in the finger when the thorn pricks it, the soul cannot say, I feel the pain; it could only say, I know that a material organ, with which I have nothing to do, is being injured. The soul would, in fact, but receive a telegram announcing what happens in some distant quarter. If a telegram comes to you from Siberia, announcing twenty degrees of cold, do you feel the sensation of cold?

Büchner. Yet “the theory that the brain is the seat of the soul is so incontrovertible that it has long been adopted in the rules of law in regard to monstrosities. A monstrosity with one body and two heads counts for two persons; one with two bodies and one head, only for one person. Monstrosities without brain, so-called acephali, possess no personality” (pp. 147, 148).

Reader. This is true; and therefore the soul certainly informs the brain. But it does not follow that other parts of the body are not informed. Hence your remark has no bearing on the question; and it remains true that the soul, as the form of the body, is directly connected with every part of the organism in which vital acts are performed.

XV. Spiritism.

Reader. May I ask, doctor, what you think of spiritism?