More important, however, than all that has been hitherto noticed is the consideration that there is no, or almost no, voluntary movement which must not at the same time be regarded as a combination of reflex actions. I mean this: Anatomical investigations show that, in the upper part of the spinal cord the number of the primitive fibres amounts to only a very small fraction of the primitive fibres of all the nerves, which are destined to call forth movement through the conscious will, that is, by the brain. But now, as the path from the brain to the nerves supplying the muscles is, with few exceptions, only through the upper part of the spinal cord, it follows that a fibre in the upper part of the spinal cord must be destined to innervate a great number of muscular nerve-fibres of the same part. A direct anastomosis (interlacing, connecting) of the fibres might be imagined, but this assumption seems highly improbable according to anatomical observations, and we are also compelled to abandon it from the circumstance that one and the same movement is now stimulated by the brain, now, in consequence of some other stimulation, is independently executed by the central organs of the spinal cord, and admits an immense variety of the most delicate and intricate modifications, whilst a direct anastomosis must necessitate the same invariable movements. In addition to this, the brain, which gives the order to execute a complicated series of movements, has itself no idea of this complication, but only a collective idea of the result (as in speaking, singing, walking, dancing, running, leaping, performing gymnastic exercises, fighting, riding, skating), so that the whole detail of execution, which is requisite for the total result intended, is intrusted to the spinal cord. (Let any one ask himself whether he knows anything of the muscular contractions necessary for uttering a word or for singing a colorature.) Accordingly the only mode of conceiving the matter remaining seems to me to be this: that the current of innervation, which carries the conscious volition of the total movement from the brain to the central organ of such movement in the spinal cord, and which is for the brain, indeed, centrifugal, but for the nerve-centre of the movement centripetal, that this current is felt as sensation by the motor centre just as well as an impression coming from the peripheral parts of the body, and that the consequence of this sensation is the occurrence of the intended movement. But it is clear that we here again see the definition of reflex movement to hold good, as soon as we resolve to employ the relative conceptions of centrifugal and centripetal currents in their right relations.
One easily sees that there is hardly a movement which, even if it is originated by the cerebral consciousness, is not first conducted once or several times to another motor centre, and there visibly executed. Consciousness can, it is true, decompose movements to a certain extent, and give a conscious impulse to any partial movement (this is indeed the way we learn to make the movement), but, in the first place, every such partial presentation will probably find no other path to the muscles than through the grey matter of the motor centres, thus always retaining the character of a reflex; secondly, even the simplest motor elements accessible to the cerebral consciousness still require highly complicated combinations of movement for their execution, into which consciousness never penetrates (e.g., the utterance of a vowel or the singing of a note); and, thirdly, if its simple elements are as far as possible intended by the conscious will, the whole movement has something extremely slow, coarse, awkward, and heavy about it, whilst the very same movement is executed with the greatest facility, speed, certainty, and elegance, if only the final result was intended by the cerebral consciousness, and the execution was intrusted to the motor centres in question. One has only to think of the phenomenon of stammering. The stammerer often speaks quite fluently if he does not at all think of the utterance, and his consciousness is occupied only with the matter of his speech, but not with the mode of realisation; but as soon as he thinks of the utterance and desires to form this or that sound by conscious volition, he does not succeed, and in its stead all sorts of concomitant movements occur, which may even become convulsive. It is just the same with scrivener’s cramp and all the above-mentioned bodily exercises, in which the main thing is that they become second nature, i.e., that the conscious will ceases to trouble itself about the details. Through this way of conceiving the matter the phenomenon becomes for the first time explicable, why often a single impulse of the conscious will suffices to introduce a long series of periodically recurring movements, which last until it is interrupted by a new volitional impulse. Without this arrangement all our ordinary actions, as walking, reading, playing, speaking, &c., would absorb an amount of the volitional impulses of the brain which must very soon result in fatigue. It, however, proves also the independence of the lower nerve-centres, and most decidedly refutes the above assumption of a direct anastomosis of the nerves. It may also now be comprehensible how it comes to pass that so many actions and occupations, whose slightest details must be attended to in their conscious acquisition, later on, with prolonged practice and habit, are performed quite unconsciously, as knitting, playing on the piano, reading, writing, &c. All the work, then, which during acquisition was done by the brain, has been handed over to subordinate nerve-centres; for these can call into play an habitual combination of certain activities just as efficiently as the brain in thinking or in learning by heart. That, however, then the activities become for the most part unconscious to the brain, gives them in respect to the brain a certain resemblance to instinctive actions, whilst indeed, in respect to the nerve-centre which presides over the activity, practice and custom is the precise opposite of instinct.
That all the phenomena hitherto considered have essentially the same underlying principle, it is not very difficult to see. We started with the reflectorial movements produced by irritation of peripheral parts of the body, and found a purpose most decidedly expressed therein, both in the result of the whole movement and in the simultaneous and successive combinations of the most different muscles; nay, in part, most decidedly expressed even in an alternating play of the antagonists. We then passed on to the reflex movements produced by means of sense-perceptions, and found here the same fact, only often with a dash of higher intelligence, in that the higher central points of the spinal cord came more into play. Lastly, we noticed that reflex actions, in which the exciting stimulus is an innervating current from the brain to the other central organs concerned, are produced by the conscious will, and did not remark here any quantitative increase of effects as compared with the reflex movements produced through sense-perceptions; naturally enough, for the intelligence revealed in reflection depends far more on the stage of development of the reflecting central organ than on the nature of the stimulus.
That, in fact, the brain also can become a central organ of reflex actions, we cannot doubt from the analogy of its structure with the other centres. In reflex actions of the ganglionic system and in individuals deprived of brains, perception by the brain is excluded; but this may very well accompany the reflex actions of the spinal cord in the case of sound organisms. In this case, however, only the stimulation, but not the will to move, is felt in the brain; but the latter must manifestly also have place if the brain itself is to be a central organ of reflection. Such cases are, however, already familiar to us; e.g., the catching at a falling glass or the parrying of a previously seen blow may have these characteristics. Accordingly we shall not be able to avoid regarding them as reflex actions, if only the link between perception of the action and the will to execute it lies outside the cerebral consciousness, which receives additional confirmation from the fact that conscious reflection would manifestly come too late. To the same category belongs a part of the not quite unconscious prelection and preluding, or the rapid answers to sudden questions, or the sudden taking off the hat at the unexpected greeting of an unknown person. Cerebral reflection frequently surpasses the reflection of the spinal cord, and prevents its occurrence; e.g., a decapitated frog scratches the nipped place on the skin, a living one hops away. Here is seen the direct transition from cerebral reflection to
conscious psychical activity, between which no line can be drawn. There follows from this the unity of the principle underlying all these phenomena. There are, therefore, only two logical ways of looking at these things: either the mind is everywhere only the last result of material processes, both in the brain and in the rest of the nervous life (then, however, purpose would also have to be everywhere denied when not posited by conscious nervous activity), or the soul is everywhere the principle lying at the basis of material nervous processes, causing and regulating them, and consciousness is only a phenomenal form of the same, brought about by means of these processes. We shall see in the sequel which of these two assumptions better suits the facts.
The next point we have to investigate is the question, whether the phenomena we are considering may be looked upon as effects of a dead mechanism, or whether we are not compelled to conceive them as consequences of an intelligence immanent in the central organs, in which case the foregoing alternative may provisionally remain undiscussed. Let us first turn to physiology. The skin of a frog’s thigh being pricked by a needle, we see both legs drawn up, provided the little piece of spinal cord from which issue the crural nerves remains intact. The prick of the needle manifestly affects only one primitive nerve-fibre, since within a circle of a certain size the position of the pricked place cannot be distinguished; the number of motor fibres put in action by the same is, however, enormously large, for it can embrace the whole body. The direct anastomosis of the sensory and motor nerves is hereby rendered improbable in the highest degree. It becomes, however, still more so by the circumstance that the same motor fibres react, when this or that place in the skin of the frog’s thigh is pricked, when accordingly different sensory nerve-fibres convey the stimulus to the centre. Besides, microscopic investigations not only give no support to this supposition, but what is more, Kölliker has directly observed the emergence of motor fibres from globules of grey nerve-matter (central organ), and it is now generally supposed that the central origin of all the nerve-fibres must be sought in the ganglion-cells, i.e., the peculiar spherical or radiated cells of the grey nerve-matter. The stimulus conducted by the sensory fibres must accordingly, in any case, be first received by the central organ, and through this be conducted to the motor nerves; in no other way could any sensory fibre possibly be in a position to act upon any motor fibre of the same centre (as is actually the case). But if all the stimuli are first received by the central organ, and are only propagated from this to the motor nerves, then the materialistic explanation of reflex actions by a peculiar mechanism of the channels of conduction becomes quite impossible; for no laws and contrivances can at all be imagined which should allow one and the same current to pass over now to near, now to remote parts, should cause the reactions to follow now in this, now in that order, nay, should even permit an alternating play of the antagonists to occur on a simple stimulus (as in the rubbing of the filliped part). The impossibility of a pre-established mechanism is, however, physiologically demonstrable in a much more striking way. If one divides the spinal cord throughout its whole length by a longitudinal section, the capacity for reflex movements is not affected; it is only limited to the half of the body irritated on each occasion. If, on the other hand, a connecting bridge be left between the two separated halves at any place whatsoever, or if, at some distance from each other, now the left and then the right half of the spinal cord be cut across, so that all the longitudinal fibres are severed, general reflex movements may be excited by stimulation of each main point. This is probably the clearest proof that the motor reaction is not a consequence of the predetermined paths of the conduction of the stimulus, but that the current after destruction of the usual channels makes for itself new paths, in order to bring about the suitable reflex movements, provided only that the parts be not completely isolated. There must then be a principle superior to the material laws of conduction of the nerve-currents, which brings about this change of circumstances, in virtue of which the courses of these currents are changed, and this principle can only be an immaterial one. This is also verified by the circumstance, that the union of reflex movements is for the most part capable of being dissolved by conscious volition and exercise.
Forcible as are these anatomical-physiological reasons, they are still not the strongest of all. If the conformity to the end in view which appears in reflex actions were one externally predetermined, brought on the scene by a material mechanism, then the capability of accommodating movements to the nature of the circumstances, this inexhaustible wealth of combinations, each of which is suitable to its special case, would be plainly inexplicable. We should rather expect a constant recurrence of a few similar complex movements, whereas a single glance at the infinite number of combinations, as exemplified in the simple case of preserving one’s balance, is sufficient to establish the conviction of an immanent fitness—an individual providence, as we have already come to know it when considering Instinct. We are absolutely obliged, then, so to represent to ourselves the event that the stimulus is perceived as idea, and through the idea of the danger or feeling of pain connected therewith the idea of relief through the corresponding counter-movement is produced, which now becomes the object of volition. That the nerve-centres of the spinal cord and ganglia possess the capacity of willing we have already settled; that the cases being strictly parallel, they must also possess sensibility is evident at once; but since no sensation can be imagined without a certain degree of consciousness, however small, they also possess a certain consciousness. The beginning and the end of the process, the perception of the stimulus and the will to move, are then the functions which we have no hesitation in ascribing to every nervous centre. The only question is, whether the link between them, the positing of design, can also be a function of conscious intellectual association of these nerve-centres? Now this must certainly be denied, for we have indeed seen, that the effects of reflexion are of so great importance to the organism, just because they so far surpass the performances of the conscious reflection of the brain in ease, speed, and accuracy. This is, however, precisely the character of the unconscious idea, as we have become acquainted with it in the case of instinct, and have learnt further to know it in other ways. Accordingly all that we have adduced in the case of instinct against its origination through conscious reflection holds here in a still higher degree, partly because the instantaneousness of the effect is more striking in the present case, and is in still greater contrast with the sluggishness of conscious thought in beings low down in the scale, partly because we have here to do in the case of animals especially with lower centres, whilst we only find results of conscious reflection at all worth mentioning where the cerebral functions of the higher birds and mammals come into play. If, on the other hand, we contemplate the animals whose chief centres are about on a par with the lower human nerve-centres, we observe the greatest obtuseness and stupidity (e.g., in most amphibia and fishes), in contrast to which one cannot help being struck by the wonderful accuracy and fitness with which instinctive actions are performed, ever increasing in significance and extent in proportion to the entire mental life of the animal. Here there is none of that hesitancy of discursive thought, none of that shrewd and cautious consideration, which we observe in higher animals, but the instinctive action instantly follows on the impression, whereas reflection would often cost even the human brain a considerable time, and, when the action is inappropriate, as may well happen in sense-illusions in the conscious perception of causes, the pernicious error is embraced with equal certainty. We are compelled to designate this attribute of the unconscious idea, in contrast to discursive thinking, an immediate intellectual intuition, and wherever we meet with the (not relatively to this or that centre, but absolutely) unconscious idea, we shall find this to be its characteristic.
Philosophy of the Unconscious Page 17