(For a Swedish translation of this section, see https://www.expertoautorecambios.es/science/?p=48.)
The soul or mind is not matter, but spirit, and of course forms no part of the body. This raises an important issue with one class who deny the immortality of the soul. There are some who deny the existence of a soul or spirit in man, to be contradistinguished from the body, and insist that what we call the mind is a mere function of the brain, and that the brain itself is intelligent.
So far as the researches of philosophy extend, there are but two primary substances in the universe, and these are MATTER and SPIRIT. All we know of these substances is certain properties and phenomena which they exhibit. Matter is known to possess the properties of Impenetrability, Extension, Figure, Divisibility, Indestructibility, Inertia, Attraction. Spirit is that which thinks, perceives, remembers, reasons, wills, and is susceptible of love, hatred, joy, and grief. The former of these properties are found in our bodies, in common with all other matter; the latter constitute the phenomena of the mind. It is not reasonable to suppose that properties so opposite to each other, inhere in the same substance, and the only rational conclusion is, that matter is not mind, and that mind is not matter. There must, therefore, ho in man an intelligent spirit, which forms no part of the body, and this is what we call the soul. We reason upon the modern and generally admitted principles of natural philosophy, and unless we are greatly mistaken, the whole system of philosophy will have to be exploded to invalidate our arguments.
The admitted properties of matter, and the admitted properties of mind, cannot inhere in, and be essential properties of the same substance. A few illustrations will make this plain.
Inertia, which is an essential property of matter, cannot inhere in the same substance with will or volition, which is an essential property of mind. Inertia is that property in matter which renders it incapable of self motion, or self-action; matter acting only as it is acted upon; will or volition, is that property of mind which renders it capable of self-determination and self-action. Now, as matter can act only as it is acted upon, and as mind has the power of self-action, they cannot be the same substance,-matter cannot be mind, and mind can not be matter. Again, matter can he moved only by physical force; matter acts upon matter by contact, and one material body has no power to act on another material body, only as their surfaces come in contact; but mind is acted upon by motives, and acts from motives, and mind acts on mind through the medium of motives without physical contact. This proves as clear as a sunbeam that matter and mind are not the same.
To insist in opposition to the above view, that mind is matter; that intelligence and volition are its inherent properties, and consequently that man has no soul, which forms no part of his body, must subvert the admitted principles of philosophy. Philosophy insists that inertia is au essential property of matter; man's body is matter, as shown above, and yet it exhibits locomotive powers, and is seen acting without any visible agent acting upon it, and hence the doctrine of the inertia of matter must be given up, or we must admit that there is a rational soul inhabiting the body, which controls it, moves it, and guides it. We see a steam engine in motion, and we know that the power of motion does not reside in any part of the machine; that it acts only as it is acted upon. We know that the steam propels it, but we know at the same time, that the steam acts only as it is acted upon; that there is an intel1igent, reasonable agent that directs the whole.
So with the body; it is an animal machine, the bones are studs and braces to support the frame, and are levers for the purpose of mechanical action; the muscles, by their contractions and distentions, operate on the bones and set the machinery in motion; but the muscles have no intelligence, or volition, and when the machine is in order, they are under the control of and are guided by the mind. The foot or hand cannot will to move; the eye cannot will to open or shut. This our own consciousness proves. Let any man try to will with his foot or hand, and his own consciousness, which is the highest proof possible, will tell him that there is no power to will in his foot or hand. Man can will, and may be conscious of willing to move his foot, but at the same time he is conscious that his foot does not will, and that he does not will with his foot, but that he, his mind, wills concerning it. The muscles are put in motion by a power superior to themselves, which must be intelligent. Now what is this power Those who deny that man has a soul, which is no part of the body, and which is an immaterial spirit, say that the brain is this self-determining, controlling and guiding power. This we deny on the ground, that it is matter, and only matter, and possesses only the properties and powers of matter. If it be said that there is something in or associated with the brain which is not matter, which is superior to matter, the whole argument is given up, for that is just what we contend for, and that superior something which is not matter, we call the soul. If it be said that the brain is only matter, then however refined it may be, it possesses only the properties of matter, one of which is inertia, directly the reverse of self-operation. The brain then cannot act only as it is acted upon, and we come back to the question, what is this superior power that sets the muscles in motion, when we will to move the foot or the hand If it now be said that it is the brain, we ask what power acts upon the brain, causing it to act on the muscles The brain being matter, can act only as acted upon. We have then got to give up the first principles of Natural Philosophy, or seek for some higher cause of the phenomenon of motion. We allow that the muscles operate on the bones, that the brain operates on the muscles, through the nerves, all the nerves and spinal marrow terminating in the brain; but we insist at the same time, that there is an intelligent soul which acts on the brain, or it would never act. This doctrine being admitted, the phenomena of matter and mind are made to harmonize without involving any philosophical contradiction, or absurdity; deny it, and the principles of Natural Philosophy, which past ages have developed and matured, are thrown back into chaos, and we have got to begin, de novo, and grope our way in search of first principles.
The above view accords with our own consciousness, Every man is conscious of thinking, but we are not conscious of thinking with any part of our body, not even the brain. That the head is the seat of the intelligence, no rational man can doubt; we are conscious that the thinking operation is carried on within the head., but no man is conscious that his brains think. The rational soul is mysteriously united to the body, and the brain is doubtless the point of union, and constitutes the medium through which the soul holds communion with the physical world without. The fact that this union is mysterious constitutes no objection, for if we deny it, there will be as great a mystery involved in the idea that the whole mental phenomena is the result of properties inherent in matter, and found only in the brain, in contradistinction from all other matter.