Chapter 9
The Action Of The Sensuous Instinct
392. We must now deal with the activity that we have called sensuous
instinct and discover how this new activity and its various functions arise
after the unique feeling has been produced and the animal constituted.
We must first note that our enquiry does not concern the origin of particular
sensations. They arise in the life instinct which, as the animal activity
producing the fundamental feeling, must feel the modifications of the
fundamental feeling caused by an alteration of its matter. We are simply asking
for the explanation of spontaneous animal movements which are made in response
to the experience of animal feelings, and which in great part tend to produce a
better, animal state.
393. We must also bear in mind that spontaneous animal movements are the effect sometimes of a single feeling and sometimes of many feelings which, as modifications of the single fundamental feeling, are unified through the unity of the feeling.
394. Later we shall discuss the association of feelings with the spontaneous movements that follow them. Here we simply want to suggest how a simple feeling can stimulate a spontaneous movement in the animal without its having recourse to knowledge and intelligence. The animal is not endowed with these faculties; it is totally limited to feeling alone.
In reply we say that every partial animal feeling is by nature connected with a feeling of the nerves. Moreover, it is a fact that a movement stimulated in the organs used for feeling is communicated to the organs used for spontaneous movement. Drowsiness and sleep is a good example of this union and connection between the nerves used for feelings and those used for external motion. The nerves controlling exterior sensitivity withdraw for respite, and at the same time the muscles cease their activity. For example, when a person falls asleep, the muscles holding the head erect slacken, the head droops and the lower jaw sags leaving the mouth open. The knees become limp, and the lower limbs no longer support the person, who begins to slip, and would fall if not held. Hence the natural position for sleep is lying down and straight, because this position does not require any use of muscular energy. Many other similar observations show how muscular energy and movements increase or decrease in parallel with the activity of external sensitivity.(181) Indeed, physiologists have firmly and incontrovertibly established the fact we are discussing, namely, that nerve movement exists where there is partial feeling, and that this movement can extend to and affect the muscles.
395. This fact allows me to argue that when the living members of the body receive an external impulse to movement, the principle or soul vivifying the members also receives the movement. Consider the kind of feeling we experience if someone else's hand or some other external force moves our leg, for example, to a different but natural position. We cannot remain entirely indifferent to the movement caused in us. If we co-operate with the movement of the leg and with the force affecting and displacing it, we are clearly active. If we resist the movement with our leg muscles, we are active in the opposite direction. Even if we neither resist nor co-operate positively with the intended movement of our leg, we are still not indifferent (this must be carefully noted); we are passive, feeling that we experience some disturbance. We feel, not without some displeasure, that our dominion over our leg is being violated, as it were. If, however, we keep the leg firmly in position, not as something dead but as something living, it remains where it is because our living energy determines it to that place and not elsewhere.(182) To displace it, the force would have to overcome the vital energy holding it there by applying some form of constraint. When, therefore, a muscle or part of our body receives initial motion from a foreign force, the animal has three choices: to resist the movement, to permit it to spread throughout the muscle without any co-operation (as if the muscle were inanimate), or to assist the impulse of the motion imparted to the muscle. Constraint is present in the first two choices, spontaneity in the third. To assist the movement in its initial stages is to alienate the constraint, the level of which depends on whether we resist or not. Normally the animal chooses to set itself spontaneously in motion, because spontaneous movement is less tiring and troublesome than the first two kinds of resistance. Moving becomes its natural state, just as previously when there was no impulse to movement from any direction, rest was its natural state.
396. Sleep is a good example for explaining more clearly the action of the sensuous instinct. By this action the animal determines itself to move when it assists and continues the minute movements of the nerves accompanying feelings. In human beings the nerves of the ear have a special bond and harmony with the muscles of the lower limbs: the movements of the acoustic nerves spread to the legs and give them the impetus for movement. Thus, when we hear music, we have to make an effort to keep our legs still, and can do this only by positively resisting the internal disturbance and agitation communicated to them, or by allowing the movement to act on our legs as if they were dead. This second kind of resistance requires even greater effort for a living human being, and opposes nature. Very young children (who do not resist nature) can be observed to start dancing as soon as they hear rhythmic sounds; animals, like the monkey and the bear, will do the same. This is the origin of dancing, which has been practised throughout history and by all peoples, particularly those closest to a state of nature.
397. We can conclude that the animal principle is subject to a law of inertia similar in some way to the law explaining the phenomena of movement in bodies. If a body is at rest, it remains so until a force impels it; if it is moving, it will continue in motion until another force returns it to rest. In the same way, if a living principle is set in motion by sensation and the tiniest movements of the accompanying nerves, it will continue in this state of activity which, in its turn, produces muscular movement that increases with the mobility proper to the muscles. Hence the human spontaneous movements that we have described.
398. Consequently, we do not need to suppose intelligence or will in the animal in order to explain this kind of movement. Instead, we must suppose a special law of inertia by which the animal spontaneously assists and continues the movements produced in it by external stimuli and its own internal vital activity (which is the real starting point of every animal function).
399. The problem of small, unfeelable nerve movements on the one hand and large muscle movements on the other (apparently a mystery to physiologists) can also be explained. The smallest movement, which becomes large by spreading to the muscle, could undoubtedly find a favourable disposition in the irritability of the muscular fibre, but irritability would certainly not suffice to explain the phenomenon because the extremely small nerve movement would never be a sufficient stimulus to arouse such great contractions in a muscle. Furthermore, it would not explain how human movements, which contain nothing violent, oscillatory or vibrative, are smooth, spontaneous and obedient to the animal element producing them. Clearly, the animal must continually co-operate with its own activity.
In my opinion the very slight movement produced in the nerve in company with feeling, together with the mechanical communication of the movement, is not the only direct cause of muscle movement, although it is the cause that stimulates spontaneous animal activity. This activity is set in motion as soon as it feels movement in one of the parts under its control. The movement, as we said, disturbs the activity and attracts it by means of its own state, so that if the activity itself did not co-operate by moving the part in response to the impetus, it would suffer further discomfort. Consequently, it costs the activity less to move the part; its action is less than that required to keep the part rigid, if we suppose the part is moved independently of itself. Once in motion, the activity, because of the law of inertia, must continue till it reaches a certain point. In addition to its own inertia there is also the inertia proper to a body. When a body is set in motion by larger movements, it does not come to rest quickly; it tends to maintain itself in motion according to its own laws. A baby, when it sees its mother smiling and caressing it, experiences a feeling of joy. The feeling, accompanied by unfeelable nerve movements, initiates muscular movements of its mouth and lips. The soul gives in to these impulses, and, assisting them spontaneously, produces the baby's smile.
400. We cannot therefore agree with Bichat, who denies animal life in the foetus and explains its movement as a simple expression of organic life.(183) We readily accept that the foetus' movements in the womb can start in the brain and nerves, and be stimulated by the sympathy between certain organs and the brain. But we maintain that these tiny movements and stimulations in the brain could never explain the large movements of the foetus and the very strong pressures it sometimes applies to the walls of the womb unless the soul itself, following the law of the sensuous instinct, were drawn into action to assist and increase the first small movements. When the soul performs such movements, it carries out a smaller action and needs less effort than when it omits the movements, granted that, if the soul remained inactive, it would experience something contrary to its nature. As we have seen, the soul is naturally so active throughout the whole body that the instinctive movement we are discussing is virtually included in the first activity itself, and depends on the law of activity which makes the soul naturally master of the body, and unwilling to suffer any loss of control.(184)
Notes
(181) Animals whose feeling is very acute respond more quickly in their movements. This explains the extraordinary agility of the bat to change direction and avoid the smallest obstacles, such as the minute threads which Spallanzani hung in a room.
(182) We should carefully note the observation made by physiologists that muscular action is as much present in the positions assumed by human beings as in movement. If we remain in a given position, the antagonistic muscles are equally and simultaneously active. When we move, the antagonistic muscles alternate in their action, and movement results.
(183) Ricerche fisiologiche intorno alla vita e alla morte, pt. 1, art. 8.
(184) Sensists have made feeling a part of intelligence, and instinct a part of will. Seeing that the movements of the foetus and other animal movements could not be attributed to the will, they attributed them to the organic complex, without considering whether there might be something between organic life and the will. But if we observe nature carefully, we notice that the pleasure-instinct comes between organic life and the will. This instinct is not a part of the will but an essentially different faculty belonging to animal life.