propose to carry this analysis any further. The psychic states whose intensity we have just defined are deep-seated states which do not seem to have any close relation to their external cause or to involve the perception of muscular contraction. But such states are rare. There is hardly any passion or desire, any joy or sorrow, which is not accompanied by physical symptoms; and, where these symptoms occur, they probably count for something in the estimate of intensities. As for the sensations properly so called, they are manifestly connected with their external cause, and though the intensity of the sensation cannot be defined by the magnitude of its cause, there undoubtedly exists some relation between these two terms. In some of its manifestations consciousness even appears to spread outwards, as if intensity were being developed into extensity, e.g. in the case of muscular effort. Let us face this last phenomenon at once: we shall thus be transported at a bound to the opposite extremity of the series of psychic phenomena.
Muscular effort seems at first sight to be quantitative.
If there is a phenomenon which seems to be presented immediately to consciousness under the form of quantity or at least of magnitude, it is undoubtedly muscular effort. We picture to our minds a psychic force imprisoned in the soul like the winds in the cave of Aeolus, and only waiting for an opportunity to burst forth: our will is supposed to watch over this force and from time to time to open a passage for it, regulating the outflow by the effect which it is desired to produce. If we consider the matter carefully, we shall see that this somewhat crude conception of effort plays a large part in our belief in intensive magnitudes. Muscular force, whose sphere of action is space and which manifests itself in phenomena admitting of measure, seems to us to have existed previous to its manifestations, but in smaller volume, and, so to speak, in a compressed state: hence we do not hesitate to reduce this volume more and more, and finally we believe that we can understand how a purely psychic state, which does not occupy space, can nevertheless possess magnitude. Science, too, tends to strengthen the illusion of common sense with regard to this point. Bain, for example, declares that "the sensibility accompanying muscular movement coincides with the outgoing stream of nervous energy:"2 it is thus just the emission of nervous force which consciousness perceives. Wundt also speaks of a sensation, central in its origin, accompanying the voluntary innervation of the muscles, and quotes the example of the paralytic "who has a very distinct sensation of the force which he employs in the effort to raise his leg, although it remains motionless."3 Most of the authorities adhere to this opinion, which would be the unanimous view of positive science were it not that several years ago Professor William James drew the attention of physiologists to certain phenomena which had been but little remarked, although they were very remarkable.
The feeling of effort. We are conscious not of an expenditure of force but of the resulting muscular movement.
When a paralytic strives to raise his useless limb, he certainly does not execute this movement, but, with or without his will, he executes another. Some movement is carried out somewhere: otherwise there is no sensation of effort.4 Vulpian had already called attention to the fact that if a man affected with hemiplegia is told to clench his paralysed fist, he unconsciously carries out this action with the fist which is not affected. Ferrier described a still more curious phenomenon.5 Stretch out your arm while slightly bending your forefinger, as if you were going to press the trigger of a pistol; without moving the finger, without contracting any muscle of the hand, without producing any apparent movement, you will yet be able to feel that you are expending energy. On a closer examination, however, you will perceive that this sensation of effort coincides with the fixation of the muscles of your chest, that you keep your glottis closed and actively contract your respiratory muscles. As soon as respiration resumes its normal course the consciousness of effort vanishes, unless you really move your finger. These facts already seemed to show that we are conscious, not of an expenditure of force, but of the movement of the muscles which results from it. The new feature in Professor James's investigation is that he has verified the hypothesis in the case of examples which seemed to contradict it absolutely. Thus when the external rectus muscle of the right eye is paralysed, the patient tries in vain to turn his eye towards the right; yet objects seem to him to recede towards the right, and since the act of volition has produced no effect, it follows, said Helmholtz,6 that he is conscious of the effort of volition. But, replies Professor James, no account has been taken of what goes on in the other eye. This remains covered during the experiments; nevertheless it moves and there is not much trouble in proving that it does. It is the movement of the left eye, perceived by consciousness, which produces the sensation of effort together with the impression that the objects perceived by the right eye are moving. These and similar observations lead Professor James to assert that the feeling of effort is centripetal and not centrifugal. We are not conscious of a force which we are supposed to launch upon our organism: our feeling of muscular energy at work "is a complex afferent sensation, which comes from contracted muscles, stretched ligaments, compressed joints, an immobilized chest, a closed glottis, a knit brow, clenched jaws," in a word, from all the points of the periphery where the effort causes an alteration.
Intensity of feeling of effort proportional to extent of our body affected.
It is not for us to take a side in the dispute. After all, the question with which we have to deal is nοt whether the feeling of effort comes from the centre or the periphery, but in what does our perception of its intensity exactly consist? Now, it is sufficient to observe oneself attentively to reach a conclusion on this point which Professor James has not formulated, but which seems to us quite in accord with the spirit of his teaching. We maintain that the more a given effort seems to us to increase, the greater is the number of muscles which contract in sympathy with it, and that the apparent consciousness of a greater intensity of effort at a given point of the organism is reducible, in reality, to the perception of a larger surface of the body being affected.
Our consciousness of an increase of muscular effort consists in the perception of (1) a greater number of peripheral sensations (2) a qualitative change in some of them.
Try, for example, to clench the fist with increasing force. You will have the impression of a sensation of effort entirely localized in your hand and running up a scale of magnitudes. In reality, what you experience in your hand remains the same, but the sensation which was at first localized there has affected your arm and ascended to the shoulder; finally, the other arm stiffens, both legs do the same, the respiration is checked; it is the whole body which is at work. But you fail to notice distinctly all these concomitant movements unless you are warned of them: till then you thought you were dealing with a single state of consciousness which changed in magnitude. When you press your lips more and more tightly against one another, you believe that you are experiencing in your lips one and the same sensation which is continually increasing in strength: here again further reflection will show you that this sensation remains identical, but that certain muscles of the face and the head and then of all the rest of the body have taken part in the operation. You felt this gradual encroachment, this increase of the surface affected, which is in truth a change of quantity; but, as your attention was concentrated on your closed lips, you localized the increase there and you made the psychic force there expended into a magnitude, although it possessed no extensity. Examine carefully somebody who is lifting heavier and heavier weights: the muscular contraction gradually spreads over his whole body. As for the special sensation which he experiences in the arm which is at work, it remains constant for a very long time and hardly changes except in quality, the weight becoming at a certain moment fatigue, and the fatigue pain. Yet the subject will imagine that he is conscious of a continual increase in the psychic force flowing into his arm. He will not recognize his mistake unless he is warned of it, so inclined is he to measure a given psychic state by the conscious movements which accompany it! From these facts and from many others of the same kind we believe we can deduce the following conclusion: our consciousness of an increase of
