The history of Man's thought is the real history of mankind. Back of all the events of history are the curious systems of beliefs for which men have lived and died. Struggling to understand himself, Man has built up and discarded superstitions, theologies and sciences.
Early in this strange and fascinating history he divided himself into two parts--a body and a mind. Working together with body, mind somehow was of different stuff and origin than body and had only a mysterious connection with it. Theology supported this belief; metaphysics and philosophy debated it with an acumen that was practically sterile of usefulness. Mind and body "interacted" in some mysterious way; mind and body were "parallel" and so set that thought-processes and brain-processes ran side by side without really having anything to do with one another.[1] With the development of modern anatomy, physiology and psychology, the time is ripe for men boldly to say that applying the principle of causation in a practical manner leaves no doubt that mind and character are organic, are functions of the organism and do not exist independently of it. I emphasize "practical" in relation to causation because it would be idle for us here to enter into the philosophy of cause and effect. Such discussion is not taken seriously by the very philosophers who most earnestly enter into it.
[1] William James in Volume 1 of his "Psychology" gives an interesting resume of the theories that consider the relationship of mind (thought and consciousness) to body. He quotes the "lucky" paragraph from Tyndall, "The passage from the physics of the brain to the corresponding facts of consciousness is unthinkable. Granted that a definite thought and a definite molecular action in the brain occur simultaneously; we do not possess the intellectual organ, or apparently any trace of the organ which would enable us to pass by a process of reasoning from one to the other." This is the "parallel" theory which postulates a hideous waste of energy in the universe and which throws out of count the same kind of reasoning by which Tyndall worked on light, heat, etc. We cannot understand the beginning and the end of motion, we cannot understand causation. Probably when Tyndall's thoughts came slowly and he was fatigued he said--"Well, a good cup of coffee will make me think faster." In conceding this practical connection between mind and body, every "spiritualist" philosopher gives away his case whenever he rests or eats.
The statement that mind is a function of the organism is not necessarily "materialistic." The body is a living thing and as such is as "spiritualistic" as life itself. Enzymes, internal secretions, nervous activities are the products of cells whose powers are indeed drawn from the ocean of life.
To prove this statement, which is a cardinal thesis of this book, I shall adduce facts of scientific and facts of common knowledge.
One might start with the statement that the death of the body brings about the abolition of mind and character, but this, of course, proves nothing, since it might well be that the body was a lever for the expression of mind and character, and with its disappearance as a functioning agent such expression was no longer possible.
It is convenient to divide our exposition into two parts, the first the dependence upon proper brain function and structure, and the second the dependence upon the proper health of other organs. For it is not true that mind and character are functions of the brain alone; they are functions of the entire organism.
The brain is simply the largest and most active of the organs upon which the mental life depends; but there are minute organs, as we shall see, upon whose activity the brain absolutely depends.
Any injury to the brain may destroy or seriously impair the mentality of the individual. This is too well known to need detailed exposition. Yet some cases of this type are fundamental in the exquisite way they prove (if anything can be proven) the dependence of mind upon bodily structure.
In some cases of fracture of the skull, a piece of bone pressing upon the brain may profoundly alter memory, mood and character.
Removal of the piece of bone restores the mind to normality. This is also true of brain tumor of certain types, for example, frontal endotheliomata, where early removal of the growth demonstrates first that a "physical" agent changes mind and character, and second that a "physical" agent, such as the knife of the surgeon, may act to reestablish mentality.
In cases of hydrocephalus (or water on the brain), where there is an abnormal secretion of cerebro-spinal fluid acting to increase the pressure on the brain, the simple expedient of withdrawing the fluid by lumbar puncture brings about normal mental life. As the fluid again collects, the mental life becomes cloudy, and the character alters (irritability, depressed mood, changed purpose, lowered will); another lumbar puncture and presto!--the individual is for a time made over more completely than conversion changes a sinner,--and more easily.
