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. [Sidenote: Intensity of feeling of effort proportional to extent of our body affected.]