Reader. The term is known, but it is used more or less properly by different persons. Our minds may deal with either sensible or intellectual objects. When we have seen a mountain, we may think of it, because we have received from it an impression in our senses which leaves a vestige of itself in our organism, and enables us to represent to ourselves the object we have perceived. In this case our thought is an exercise of our imagination. When, on the contrary, we think of some abstract notion or relation which does not strike our senses, and of which no image has been pictured in our organic potencies, then our thought is an exercise of intellectual power. In both cases our brain has something to do with the thought. For in the first case our thought is an act of the sensitive faculty, which reaches its object as it is pictured, or otherwise impressed, in our organic potencies, of which the headquarters are in the brain. In the second case our thought is an act of the intellectual faculty, which detects the intelligible relations existing between the objects already perceived, or between notions deduced from previous perceptions; and this act, inasmuch as it implies the consideration of objects furnished to the mind by sensible apprehension, cannot but be accompanied by some act of the imaginative power making use of the images pictured in the organic potencies. Now, doctor, when you say that “the brain is the seat and organ of thought,” do you mean that both the intellectual and the imaginative thought reside in the brain and are worked out by the brain?
Büchner. Of course. For “comparative anatomy shows that through all classes of animals, up to man, the intellectual energy is in proportion to the size and material quality of the brain” (p. 107).
Reader. You are quite mistaken. The brain is an organ of the imagination, not of the intellect. And even as an organ of imagination it is incompetent to think or imagine, as it is only the instrument of a higher power—that is, of a soul. To say that the brain is the organ of intellectual thought is to assume that intellectual relations are pictured on the brain; which is evidently absurd, since intellectual relations cannot be pictured on material organs. Every impression made on our brain is a definite impression, corresponding to the definite objects from which it proceeds. [pg 085] If our intellectual thought were a function of the brain, we could not think, except of those same definite objects from which we have received our definite impressions. How do you, then, reconcile this evident inference with the fact that we conceive intellectually innumerable things from which we have never received a physical impression? We think of justice, of humanity, of truth, of causality, etc., though none of these abstractions has the power to picture itself on our brain. It is therefore impossible to admit that the intellectual thought is a function of the brain. With regard to the working of the imagination, I concede that the brain plays the part of an instrument; but how can you explain such a working without a higher principle? If our soul is nothing but “a product of matter,” since matter is inert, our soul must be inert, and since matter has only mechanical powers, our soul must be limited to mechanical action, that is, to the production of local movement. Now, can you conceive imagination as a merely mechanical power, or thought as the production of local movement?
Büchner. Yes. “Thought,” says Moleschott, “is a motion of matter” (p. 135).
Reader. It is perfectly useless, doctor, to make assertions which cannot be proved. Moleschott is no authority; he is a juggler like yourself, and works for the furtherance of the same Masonic aims. Let him say what he likes. We cannot but laugh at a thinker who can mistake his thought for local motion.
Büchner. You, however, cannot deny that, while we are thinking, our brain is doing work. But how can it do work without motion?
Reader. I do not deny that, while we are thinking, our brain is doing work. I merely deny that the movements of the brain are thoughts. As long as we live, soul and body work together, and we cannot think without some organic movements accompanying the operation. This every one admits. But you suppress the thinking principle, and retain only the organic movements. How is this possible? If thought consists merely of organic movements of the brain, how does the motion begin? The brain cannot give to itself a new mode of being. To account for its movements you must point out a distinct moving power, either intrinsic or extrinsic, either a sensible object or the thinking principle itself. When the motion is received from a sensible object, the movements of the brain determine the immediate perception of the object; and when the motion results from the operation of the thinking principle, the movements of the brain determine the phantasm corresponding to the object of the actual thought. Thus immediate perception, and thought, or recollection, are both rationally explained; whilst, if the thinking subject were the brain itself, how could we recollect our past ideas? When the movement caused by an object has been superseded by the movement caused by a different object, how can it spontaneously revive? Matter is inert; and nothing but a power distinct from it can account for the spontaneous awakening of long-forgotten thoughts.
Büchner. Matter is inert, but is endowed with forces, and wherever there are many particles of matter they can communicate movement to one another. Hence, “in the same manner as the steam-engine [pg 086] produces motion, so does the organic complication of force-endowed materials produce in the animal body a sum of effects so interwoven as to become a unit; and is then by us called spirit, soul, thought” (p. 136).
Reader. Pshaw! Are spirit, soul, and thought synonymous? Do thoughts think? When you perceive that two and two make four, is this thought the thinking principle? And if the soul is “a sum of mechanical effects so interwoven as to become a unit,” how can you avoid the consequence that the soul consists of nothing but local movement? But if the soul is local movement, it has no causality, and cannot be the principle of life; for local movement is only a change of place, and has nothing to do with perception, judgment, reasoning, or any other operation of the thinking principle. Can local movement say, I am? I will? I doubt? Can local movement recollect the past, take in the present, foresee the possible and the future? Can local movement deliberate, love, hate, say yes or no? To these and such like questions science, reason, and experience give an unequivocal answer, which the president of a medical association should have carefully meditated before venturing to write on the subject.
Büchner. Yet “the mental capacity of man is enlarged in proportion to the material growth of his brain, and is diminished according to the diminution of its substance in old age” (p. 110). “It is a fact known to everybody, that the intelligence diminishes with increasing age, and that old people become childish.... The soul of the child becomes developed in the same degree as the material organization of its brain becomes more perfect” (p. 111). “Pathology furnishes us with an abundance of striking facts, and teaches us that no part of the brain exercising the function of thought can be materially injured without producing a corresponding mental disturbance” (p. 119). “The law that brain and soul are necessarily connected, and that the material expansion, shape, and quality of the former stands in exact proportion to the intensity of the mental functions, is strict and irrefutable, and the mind, again, exercises an essential influence on the growth and development of its organ, so that it increases in size and power just in the same manner as any muscle is strengthened by exercise” (p. 122). “The whole science of man is a continuous proof in favor of the connection of brain and mind; and all the verbiage of philosophical psychologists in regard to the separate existence of the soul, and its independence of its material organ, is without the least value in opposition to the power of facts. We can find no exaggeration in what Friedreich, a well-known writer on psychology, says on this point: ‘The exhibition of power cannot be imagined without a material substratum. The vital power of man can only manifest its activity by means of its material organs. In proportion as the organs are manifold, so will be the phenomena of vital power, and they will vary according to the varied construction of the material substratum. Hence, mental function is a peculiar manifestation of vital power, determined by the peculiar construction of cerebral matter. The same power which digests by means of the stomach, thinks by means of the brain’ ” (pp. 124, 125).