the aid of which we ordinarily grasp the significance of the relationship are banished. We seem to ourselves to realize with a good deal of vividness what is meant by the parallelism of mind and brain so long as we are permitted to conceive the two as phenomena of the one substance, as manifestations of the same underlying reality, as aspects of one thing, as at bottom identical, as having an inner connection, etc. If we lose these phrases, how shall we conceive it? Minds and bodies seem to float apart, and the imagination is left brooding upon a void. But in considering this objection it is well to remember that it is not merely against the doctrine of parallelism that it can be brought. Material analogies have always been pressed into the service of the attempt to conceive clearly what is assumed to be not material. How can it be otherwise? The very words we use to denote mental functions of every description have been exhumed from the soil, torn from the world of matter, and they have been transported to another sphere still reeking with earthly odors. It is only the purgatorial fires of reflection that can purge these away, and they sometimes seem unequal to the task. Of what absurdities may one not be guilty when one has described consciousness as an "internal light"? What is suggested to the mind by the word "intuition"?2 When we speak of consciousness as an "agent," where do we get the meaning of the word? What fallacies may not lurk behind the ambiguity of the phrase "direction of the attention"? That one should always and under all circumstances keep one's mind free from the materialistic associations of such forms of expression, it is too much to expect, but it does not seem unreasonable to expect a man to exercise a jealous watchfulness lest he be tripped up by them. So it is with parallelism. For the purposes of common life, and for the purposes of many special psychological investigations, it may matter little that a man loosely conceives of mind and brain. as "manifestations," "aspects," or "sides." But if he takes such conceptions seriously, and builds a theory upon them, he is building upon sand. A man is not in duty bound to be a metaphysician at the breakfast table, but when he does set out to be a metaphysician, he ought to be a good one. 1 Hamilton, "Lectures on Metaphysics," XI. 2 McCosh, "First and Fundamental Truths," Part I, Chapters I-IV. CHAPTER XXI THE MAN AND THE CANDLESTICK So much for the general conception of parallelism and its justification through the assumption of an "inner identity." It is now time that we ask ourselves how the parallelist may know that mind and matter are parallel, even as a matter of "brute fact." The reflective reader will see that, as in the "Thousand-and-one Nights" the Story of the Little Hunchback leads on to the Story of the Christian Merchant, and that to the Story of the Sultan's Purveyor, so Clifford's exposition of the doctrine of parallelism, as found in the essay on "Body and Mind," leads naturally to the Story of the Man and the Candlestick. Certain difficulties, which enter and make their bow in the first essay, must be allowed to speak their lines in the second, and must step out into the glare of the footlights, that they may be inspected by the audience. We have seen that the argument for the parallelism of consciousness and cerebral activity carefully distinguishes between the external object, the retinal image of that object caused by rays of light from it entering the eye, the cerebral image due to the disturbance of the retina, which cerebral image exists in the region of the optic thalami, and the mental image, which constitutes the perception of the object. These four appear to be quite distinct from each other, and to be divisible into two widely different classes. The external object, the disturbed retina, and the stimulated ganglion belong to the one class. They are all matter in motion. They stand to each other in relations of causality, and the investigation of the conditions of all three falls within the province of the science of mechanics. The mental image, on the other hand, stands by itself. It cannot be given a place in the same series with the others, but it is "parallel" to one of them, to the cerebral image. It is not caused by the disturbance in the ganglion, but first comes into being with it. It is mind, the other three are mat The only ter, and between mind and matter there is a gulf fixed. point at which there is any hope that a "bridge" may be thrown across the gulf is at the cerebral disturbance, for there the mind seems to come, if one may use such a phrase, nearest to matter. Let O represent the object, RI the retinal image, CI the cerebral image, and MI the mental image, and we may express the relations of the four to each other thus: We are to conceive O, RI, and CT as belonging to an order of things in which MI can find no place. It can only be parallel to something which has a place in that order. But even in the essay in which Clifford so carefully fixes these distinctions, there occur certain sentences which seem to obliterate them and to confuse the scheme. Thus we are told that "that which I call your brain, the material fact, is merely my perception." 1 Does this mean that O is not an inhabitant of a different sphere from that inhabited by MI? Does it mean that it is identical with MI-not identical in the loose sense in which men use the word when they speak of one thing as being the "substance" or "underlying reality" of something else, but identical in a strict sense? If O is not something external, but is really my perception, i.e. is MI, then what is the relation of CI, which is supposed to be in the same world with it, and to be a thing of the same kind, to the MI with which it is assumed to be parallel with which, we seem justified in saying, it has been proved to be parallel, if the argument for parallelism has any weight at all? The difficulty here suggested does not have to be hunted out from its cover, but stalks boldly into the open and menaces us of its own accord, in Clifford's essay "On the Nature of Things-inthemselves": "Suppose that I see a man looking at a candlestick. Both of them are objects, or phenomena, in my mind. An image of the candlestick, in the optical sense, is formed upon his retina, and nerve messages go from all parts of this to form what we call a cerebral image somewhere in the neighborhood of the optic thalami in the inside of his brain. This cerebral image is a certain complex of disturbances in the matter of these organs; it is a mate 1"Lectures and Essays," Vol. II, p. 64. rial or physical fact, therefore a group of my possible sensations, just as the candlestick is. The cerebral image is an imperfect rep resentation of the candlestick, corresponding to it point for point in a certain way. Both the candlestick and the cerebral image are matter; but one material complex represents the other material complex in an imperfect way. "Now the candlestick is not the external reality whose existence is represented in the man's mind; for the candlestick is a mere perception in my mind. Nor is the cerebral image the man's perception of the candlestick; for the cerebral image is merely an idea of a possible perception in my mind. But there is a perception in the man's mind, which we may call the mental image; and this corresponds to some external reality. The external reality bears the same relation to the mental image that the (phenomenal) candlestick bears to the cerebral image. Now the candlestick and the cerebral image are both matter; they are made of the same stuff. Therefore the external reality is made of the same stuff as the man's perception or mental image, that is, it is made of mind-stuff. And as the cerebral image represents imperfectly the candlestick, in the same way and to the same extent the mental image represents the reality external to his consciousness. Thus in order to find the thing-in-itself which is represented by any object in my consciousness such as a candlestick, I have to solve this question in proportion, or rule of three: As the physical configuration of my cerebral image of the object, is to the physical configuration of the object, so is my perception of the object (the object regarded as complex of my feelings) to the thing-in-itself." 1 It is extremely desirable that we should get these several entities and their relations quite clear. According to the parallelistic scheme, we may try to represent them in the following formula: 1 Op. cit., pp. 85, 86. It is not necessary to suppose that Clifford occupies a different standpoint in his two essays. The essay on " Body and Mind" was printed in the Fortnightly Review, December, 1874; that on "The Nature of Things-in-themselves was printed in Mind, January, 1878, but it had been read before the "Metaphysical Society" in 1874. See Pollock's Introduction, Vol. I, p. 39. Here is the candlestick, or object; RI is the man's retinal image, CI his cerebral image, MI his mental image; similarly R'I' is my retinal image, C'I' my cerebral image, and M'T my mental image or perception. We have, thus, before us an object, the candlestick at which the man is looking, two brains, and two minds, or, at least, two perceptions, which are parallel to the two brains. But in this formula we look in vain for one of the things mentioned in the above extract, the X which is to be discovered by the aid of the mathematical proportion with which the extract ends, the truly external object. To understand the significance of this object we have to bear in mind that Clifford does not regard brains as the only things in nature that have psychic parallels. He looks upon all nature as animated, i.e. he believes that just as minds correspond to cerebral activities, so something akin to consciousness, something more or less like it, mind-stuff corresponds in the same way to all motions in matter. "A moving molecule of inorganic matter does not possess mind or consciousness; but it possesses a small piece of mind-stuff. When molecules are so combined together as to form a film on the underside of a jellyfish, the elements of mind-stuff which go along with them are so combined as to form the faint beginnings of sentience." 1 Even such a thing as a candlestick has, accordingly, we will not say a mind, but, at all events, a certain amount of mind-stuff. But Clifford regards a man's mind as the reality which we perceive as his brain, as the thing that we must conceive as truly external. The mind-stuff of the candlestick, and of every material object, must be granted a similar externality. It is the "reality" of the material thing; it is the thing-in-itself, as contrasted with the thing as perceived, the merely material. If we take all these rudimentary souls into account, we must amend our formula as follows: C'I' M'I' -- That is to say, we must recognize a world of material things, which belong to the one order and interact with each other according to the laws of mechanics; and we must recognize that each material thing has as its parallel a psychic thing, which belongs to |