From time immemorial people have wondered why it is that after death
a person ceases to think, move or speak. "It is because the
soul has left the body,' some answered. Death is the separation of the soul from the body.
O. Yakhot: What is Dialectical Materialism?
Date: 1965
Source: What is Dialectical Materialism?, pp. 62-76
Translated by: (from the Russian) Clemens Dutt
Published: Progress Publishers, Moscow
Transcription/HTML Markup: Mike B. for MIA, 2014
Public Domain: Marxists Internet Archive (2014). You may freely copy, distribute, display and perform this work; as well as make derivative and commercial works. Please credit “Marxists Internet Archive” as your source.
From time immemorial people have wondered why it is that after death
a person ceases to think, move or speak. "It is because the
soul has left the body,' some answered. Death is the separation of the soul from the body.
Body and soul! For countless centuries people have tried to guess at the relationship between the body and what is called the soul or, more correctly, human consciousness. But it proved incredibly difficult to solve this problem. How can one study something that is invisible, colourless and odourless, that cannot be heard or touched. For such is our consciousness, thought, sensation. No one can feel my pain except myself. No one knows what I am thinking unless I speak about it. What then is thought? For centuries idealists and the Church have speculated about these questions.
The Bible says that God created man out of clay, earthly dust. This dust would have remained dead if God had not given it a soul. Only then did it begin to live, move and think. The source of life and thought, according to religious teaching, is the soul, the spiritual principle. It is the "divine spark" in man. Without the soul, the body cannot exist, is dead.
But the soul, it is alleged, can quite well do without the body. It enters the body at birth and leaves it at death. To this day recognition of "life beyond the grave" is the main basis on which all religious sects rely. This is because it is just here that the churchmen can give the freest rein to their imagination. Who can check what we say?' they think. "There are no witnesses." Nine centuries ago the Persian scientist, philosopher and poet Omar Khayyam stressed this idea:
Strange, is it not? that of the myriads who
Before us pass'd the door of Darkness through,
Not one returns to tell us of the Road,
Which to discover we must travel too.
"Witnesses", however, have been found but we shall speak of that later.
What is important now is to clarify the nature of the idealist-religious conception of the relation between the material and the spiritual. It consists in the following: 1) the spiritual (consciousness) exists prior to the material; 2) the former can exist without the latter, i.e., it does not depend on it. The material is "mortal", destructible, whereas the ideal is eternal, indestructible.
Let us see, however, whether this is true.
Consciousness includes thoughts, wishes. They are primarily characteristic of human beings. Without someone who senses, there are no sensations; without someone who wishes, there are no wishes. There is no will, if there is no one to display it. Apart from man, outside him, neither will, nor sensations, nor wishes, nor other manifestations of consciousness, mind, thought, ever occur.
As you know, nature, matter, existed even when man with his consciousness, his mind, had not yet come into existence. Hence, it is clear that nature, matter, is primary and consciousness, thought, is secondary. It may be asked: since there were other living organisms prior to man, did they not possess consciousness? It is true that some animals, too, possess rudiments of consciousness. They may have, for example, the sensation of colour or smell and a certain degree of imagination. But even these rudiments of consciousness arose comparatively recently, when animals first appeared on Earth.
It follows from what has been said that nature existed not only prior to man but prior to living organisms in general and therefore independently of consciousness. It is primary. But consciousness could not exist prior to nature. It is secondary. This is one of the major proofs of the materialist solution of the fundamental problem of philosophy. But it is not the only one. Some of them you know from daily experience.
It was noticed long ago that a serious wound to a limb could cause fainting: loss of consciousness. Science has established that fainting-loss of consciousness-arises as result of cerebral anaemia, acute disease of the cardio-vascular system, serious trauma or loss of blood. Hence, consciousness depends on processes taking place in the body, brain or nerves. It is well known that a drunkard gradually destroys his bodily organism: the heart action deteriorates, the live “gives up", digestion is impaired. As a result the drunkard loses his human characteristics: his consciousness is clouded he speaks thickly, at times things go as far as complete loss of consciousness. Impairment of the body leads to impairment, or loss, of consciousness.
Here is another example. Everyone knows that if you an tired or do not feel well, it is difficult to think. On the other hand, it suffices to take a rest or physical exercise in order to feel better and be able to think clearly again.
Thus, we again reach the conclusion that there is not and cannot be consciousness without matter. But is all matter. capable of thought? It is enough to look at the world around you to be able to answer no. A stone, for instance, does not think, nor does any inanimate object. Many organisms show no signs of consciousness. When then did consciousness arise?
Modern science has proved that living nature arose from non-living nature. This is a very important conclusion. Idealists maintained that living nature has nothing in common with non-living nature. Animate and inanimate objects, they argued, are quite different from one another. Only the former are able to move, multiply and grow. The difference is indeed vast. No explanation of what was common to both of them could be found. So the opinion was formed that the living organism is actuated by a special "vital force" implanted by God, and that this makes it quite different from non-living nature. Is this view correct?
A living organism differs, of course, from non-living nature. At the same time the two are inseparably linked. The living organism, for example, consists of chemical elements such as carbon, hydrogen, oxygen, iron, sulphur, phosphorus, etc., which are the same as those often met with in non-living nature. The living organism does not possess a single element that is not found in non-living nature. The connection between the two is obvious. By analysing such facts, science proved that living matter is derived from non-living matter.
The Soviet scientist, Academician Oparin, has advanced a materialist hypothesis of the origin of life on Earth from non-living matter. But the origin of life on Earth, of the first cell, does not mean the appearance of consciousness. Only the first rudiments of consciousness came into existence at the same time as life.
Consciousness is bound up with the nervous activity of a definite part of the big cerebral hemispheres. As was shown by the Russian scientists Ivan Sechenov (1829-1905) and Ivan Pavlov (1849-1936), it is based on physiological processes taking place in the higher sections of the brain. These sections of the brain are themselves the product of a long evolutionary history, in the course of which the nervous system developed and its activity became more complex. Animal behaviour also developed and became more complex, until at last the human brain appeared and with it human consciousness.
The higher manifestations of nervous activity are bound up with the cortex of the big hemispheres. This is clearly seen by comparing the development of the nervous system and the corresponding increasingly complex behaviour of animals. In fishes, for example, owing to the absence of a cerebral cortex we encounter only the simplest reflexes.1 The reflexes of birds are much more complicated, since they possess the elements of a cortex. The reflexes of dogs are still more complex, their cortex being much more highly developed. And in the anthropoid apes every voluntary movement depends on the cortex of the big hemispheres. Nevertheless in the case of animals one cannot speak of thought in the true sense of the word. Thought is human thought, bound up with the emergence, during the process of evolution, of the highest form of the motion of matter, that of the human brain.
Thus, consciousness is a product only of highly organised matter, a product of the activity of the brain. Consciousness is a function of the brain. It cannot exist without the brain, which is its material substratum. Sechenov wrote: "Man's whole boundless world of consciousness, feeling, thought and will is governed by the activity of the big hemispheres.” Pavlov, who continued Sechenov's work, showed that mental activity is based on material processes taking place in the human brain. These are physiological processes located in the big cerebral hemispheres. "Mental activity,' Pavlov wrote, "is the result of the physiological activity o a definite mass of the brain."
Let us begin the story of this interesting case with the actual words of its hero. “Shortly after my death I returned home and entered technical school," related V. D. Cherepanov, recalling a very important episode in his autobiography. This is how it happened.
Cherepanov, a Soviet soldier, was severely wounded during the last war. "Acute loss of blood, third degree shock," said doctors. In hospital his condition went from bad to worse. He lost consciousness. After some time, the case history records: "Death from severe loss of blood and shock, 19 hours, 41 minutes, March 3, 1944." The patient was dead. But then surgeon Professor Negovsky came to the hospital. He was making a tour of front-line hospitals with a team of doctors special, complex means they brought Cherepanov back to life. His heart began to beat again, breathing was restored.
When they asked the ex-corpse if he knew what had happened to him, he replied: "Yes, I was brought back from the other world, for I was dead." "What did you see in the other world?" "I lost consciousness before I died and I did not regain it until after the operation… I was asleep during my death."
And so, a witness had returned from the "other world" and he had not discovered anything there! If death is the ration of the soul to the "other world", then Cherepanov's resurrection should mean the "return" of his soul from that world. But nothing of the sort happened.
Consider this example carefully. What actually happened? The organism was living and working, consciousness, too, active. Then, as the result of severe loss of blood the human organism lost a number of its vitally important functions following which consciousness disappeared. The man died. But his consciousness was not transferred to the "other world”. It simply disappeared with the disappearance of these vitally important functions. Subsequently, the doctors operated on his body by purely material means and consciousness was restored!
It cannot but be agreed that this is proof that consciousness depends on the body, in fact on the brain. This is confirmed by the fact that life can be restored if death has occurred not more than 5-7 minutes previously. After a longer time processes take place in the brain which lead to its definitive destruction. In such a case, the heart's action can be restored, but not that of the brain, in which so-called irreversible processes have taken place. Consciousness is irretrievably lost because the work of the brain has ceased forever. Thus science has furnished yet another argument confirming the dependence of consciousness on matter.
The Russian revolutionary democrat, Herzen, wrote that the assertion that the soul could exist without the body was like saying that a black cat could go out of a room leaving the black colour behind. Just as a swallow cannot fly without wings, so the soul cannot exist without the body. The body decays, and with it the "soul", i.e., consciousness.
What is the nature of thought which is produced by the brain?
Take any thought, any utterance, such as: "I see a birch tree" or "The plan was fulfilled 107 per cent." It is shown that what we have in mind is not the birch tree but the thought of it, of reality not the plan but the thought of it. In other words, we have in our minds concepts of the objects and phenomena that we have encountered in the world. All thought consists of such concepts. In the statement "snow is white", for example, the thought is expressed by the concepts involved in the words "snow" and "white". Where do these concepts come from? They come from life, from reality. Snow really is white. Objects exist objectively and they are the basis of the concepts that we form of them. The birch tree exists first, and then comes my concept of it. Concepts, therefore, are secondary. Reality comes first and then the reflection of it in thought. That is why Lenin called thought a copy, reflection or photograph of reality. Reality is reproduced, copied or photographed in thought.
We have explained that nature, matter, existed at a time when there was no consciousness, for it had not yet arisen. Man's consciousness depends on the state of his organism, his nervous system. Thinking is performed by the brain, which is the organ of thought: consciousness is the function of the brain. Consciousness reflects being; hence being is primary and consciousness secondary, derivative.
It must be pointed out that the mere recognition of the secondary nature of consciousness is not enough. It is essential to know its true nature as well, for there are materialists who admit the secondary nature of consciousness but who cannot correctly explain its true nature. They say that the brain secretes thought just as the liver secretes bile. In their view, thought is a secretion of the brain, which makes it and secretes it just as the internal secretory glands make and secrete other substances necessary for the physiological activity of the organism. The philosophers who hold this view of thought are called vulgar materialists, because they conceive thought in a crude, vulgar, over-simplified way. This view was advocated in the 19th century by the German philosophers Karl Vogt and Ludwig Buchner and the Dutch philosopher Jacob Moleschott. Engels called them cheap peddlers of materialism.
Some modern bourgeois philosophers follow in their footsteps, nor are they alone to do so. Some British doctors, for instance, assert that they have succeeded in "weighing the soul". They say it weighs 30 grams. This is a vulgar conception because the whole complicated process of thought is crudely reduced to a matter of 30 grams in weight. Consciousness is identified here with matter. But if that were the case, why can't it be seen? Starting from such a notion it is impossible to understand what our desires, will and thoughts are. For they are of an ideal rather than a material nature. And fantasy is not only not material, but may even be about things that do not even exist in nature. Vulgar materialism cannot answer these questions.
Idealists try to exploit the importance of the vulgar materialists in order to discredit materialism as a whole. Thus, the contemporary bourgeois philosophers Wheelwright and Hospers maintain that materialism recognises only what is material and denies the existence of the spiritual, conscious- ness and human volition. In other words, they identify the vulgar materialist standpoint of Voght, Büchner and Moleschott with Marxist-Leninist theory. The could not be more mistaken. Dialectical materialism has nothing in common with vulgar materialism. Its conception of the essence and significance of mind, of consciousness, is aimed not only against the idealists, but the vulgar materialists as well.
Lenin sharply criticised the vulgar materialists for their identification of consciousness with matter. He showed that consciousness is not of a material nature. It is a copy, an image, of reality. But the brain does not reflect or photograph reality like an ordinary camera. Reality is transformed in the human brain in the sense that it is not the objects themselves that are to be found there, but their ideal image. Marx wrote of our thought: "The ideal is nothing else than the material world reflected by the human mind, and translated into forms of thought."2
We have seen that human consciousness is the property of highly organised matter, the brain, to reflect reality. Thought must not be confused with the processes that go on in the brain. These processes are the material basis of thought. But thought itself is a more complex phenomenon than the physiological processes taking place in the brain. Consciousness, thought, is the highest form of the motion of matter.
Human thought is fundamentally different from what is sometimes rather inaccurately called "thought" in animals.
Experiments with monkeys have provided interesting findings. An apple is presented to them but they cannot reach it because a fire stands in the way. However, the monkey is "taught' that he can take water from a nearby barrel, extinguish the fire and obtain the apple. And he does obtain it in this way. The monkey is then faced with new conditions. The apple is on a board on a pond and a barrel of water is put some distance away. The task is the same: to extinguish the fire and reach the apple. The monkey can take water close at hand, the board is surrounded by it. But the monkey laboriously fetches "the" water that is in the barrel.
What does this experiment show? It shows that monkeys do not form the concept "water"; its general properties are unknown to them. The monkey's thought is directly connected with surrounding objects. Moreover, it is impossible without direct connection with them. Hence, the monkey "thinks" only when objects are in front of it. Then it discovers the elementary connection between them. But if the objects an not in front of it, it cannot "think".
Man's thought, on the other hand, is qualitatively different He becomes acquainted with objects in the course of labour and scientific activities and studies their properties. He notices that water in a barrel, a pond, a well, a river, etc., has the same properties, its ability to extinguish fire, for example He forms the concept "water". This is not water in an particular place, but "water" in general. It is an abstract concept. In this case, man abstracts from the actual forms, from concrete objects, and singles out their common properties. These characterise the object contained in the concept in question.
When we speak of the concept "tree", we are concerned with the general properties that characterise any tree, and not those belonging to a particular tree visible from a window. We are abstracting from actual trees. That is why the concept is called abstract, it is this characteristic feature of human thought, its abstract character, that is unattainable by animals. Why is this?
The point is that the development of the human brain from early childhood proceeds under the decisive influence of speech. When at about nine months a baby begins repeatedly to say "mama" this is a sure sign that it is beginning to make out what is happening in the world. How does this occur? On the basis of two sources: the child's poor experience of life and the words of people around him.
A child plays with a ball. He discovers that it is round and soft. He plays with various kinds of balls, yellow, green, etc., and each time perceives "this ball". In time the word "ball" evokes in him the idea of a "ball in general". He now knows the concept "ball". And it is expressed in a word. Our thoughts, too, are expressed in speech. But we have already pointed out that our thought is abstract, it takes place on the basis of general concepts.
What makes it possible for us to abstract, to single out, the principal features of an object from the object itself. The possibility is given us by words, speech. The word "ball' indicates that it is a question of ball in general, and not merely a particular ball. Abstract thought cannot be expressed except in words.
From childhood man's consciousness is formed on the basis of words, of language, for our thoughts are expressed by means of them. In the process there gradually arises something that is characteristic of man alone: thought becomes loosely bound up with speech. Human consciousness, thought, cannot be separated from speech. An indissoluble, organic unity of language and thought becomes established.
Engels stressed that it was the appearance of articulate speech that enabled the ape's brain to develop gradually into the human brain. How did this happen?
The following example may help us to find the right answer. History records several examples of children being reared by wolves. One such case was discovered in India in 1956. A she-wolf carried off a little girl less than three years old. When found some years later the child ran about on all fours, imitated animal noises and, of course, could not speak. It is not surprising that the child copied the animals in everything, but there is one curious detail. All efforts to teach the child to speak ended in failure. The human characteristic, consciousness, of the little girl was not restored. She could not become accustomed to the new conditions of life, and died (not a single child in the known cases of this sort has ever survived beyond childhood).
The following question arises here. The child was born with a normal human brain. As she grew, her brain obviously grew as well. Why then did she prove to be so hopelessly backward in the ability to think? On the basis of what we have said, you can easily answer this question for yourself. It is evidently not enough to have a biologically normal brain in order to display human consciousness. One must also live in society, in a collective. Outside of the collective there is no human thought. It arises as a result of man's life in society. Thought can make its appearance only when, on the one hand, it reflects nature and, on the other hand, when man enters into definite relations with other people in the course of labour, productive activities. Labour created man, human society. It is through labour, productive activities, that man's brain, his consciousness, developed. That is why Marx points out that from the very outset consciousness is a social product and will remain so as long as people exist. Consciousness is a product of man's life in society.
This implies that outside of society there can be no consciousness, just as there can be no speech or language. Thought arises and develops only in the process of labo productive activity, for only under such conditions can m actively influence nature. By acting on nature, man develops also his consciousness. It is only in the process of labour that man more and more profoundly reflects objects in his consciousness, compares them, notices what is common to them and forms definite concepts. In the course of practical activity, too, man studies the connections and relations existing between objects. Thus gradually, as material production developed, human consciousness also developed and became perfected.
Engels revealed the process of the shaping of thought a: language in his essay entitled "The Part Played by Labour the Transition from Ape to Man". He showed that the first step in the transition from the ancestral anthropoid ape man was the achievement of an erect gait. And this came about because man began to use natural implements of labour. Thus man's fore-limbs became free and began to be perfected in the course of labour activities, gradually leading to the development of the human hand. It is not only the organ of labour but the result of labour.
The employment of natural implements, however, is still not labour in the true sense of the word. Labour itself has also undergone development in the course of history. True labour began only when man artificially created the first implements of labour. The ape can use natural implements, but cannot make them. The making of the first implement however, did not yet mean the emergence of human society It was only the beginning of the long process that led to the transformation of the ape into man and, therefore, to the shaping of consciousness. This was the period of the shaping of man and human society.
Speech, too, arose during this period. The point is that during the process of joint labour, production, people felt the need to speak to one another. This need, said Engels, led I the development of an appropriate organ; the undeveloped larynx of the ape underwent a gradual but steady transformation, and the organs of the mouth gradually learnt to pr flounce one articulate sound after another. Thus arose articulate speech, language, as the means of exchanging thoughts, the medium of intercourse between people, the material envelope of thought.
The unity of language and thought follows from the very nature of the latter. It is only in words that thought, as it were, becomes real. While inside a man's head, thought is, as it were, dead and inaccessible to other people. Hence Marx pointed out that language is the immediate reality of thought. This means that thought does not exist outside of the material envelope of language. Even when we do not express our thoughts aloud, but only think to ourselves, we still clothe them in the dress of words, of language. Thanks to language, thoughts not only take shape but are transmitted to other people. And by means of writing they are even handed down from generation to generation.
Yet it would be a mistake to conclude from the above that language and thought are identical. They are parts of a unity but they are not one and the same phenomenon. Thought reflects reality. Language, however, is a means by which thoughts are transmitted to other people. Thought is directly connected with reality. Language is connected with reality not directly but through thought. This signifies that the brain directly "photographs" phenomena and their connections in the world, giving rise to our concepts and thoughts. By means of language we only transmit them to other people.
In this connection, the following question often arises. If thoughts reflect or photograph reality, how are we to explain the existence of fantasies, fancies, to which no object in nature corresponds?
For example, when there was as yet no artificial Earth satellite, the Russian scientist Konstantin Tsiolkovsky, a father of rocketry, "envisaged" it already in the early years of the present century. Does this not indicate that thought is primary and not secondary? Does it not contradict materialism?
Lenin noted that the existence of fantasy inevitably con- fronts people with such questions. The opinion may be formed that thought arises independently of surrounding reality. Here we have the roots of idealism: a basis is provided for drawing the idealist conclusion that thought can arise apart from reality or even in defiance of it. Let us see whether there is any basis for such a conclusion.
Let us recall the following fact. At the beginning of the present century Lenin set about the creation of a party of a new type. It was just at this time that in his work What Is To Be Done? the leader of the proletariat issued his famous call: 'We must dream!" What did Lenin dream of? He dreamt of a mighty Communist Party. It is well known how accurately his dream became a reality. It was not long before such a party was formed. Life itself, reality, gave rise to Lenin's dream, his audacious thought.
Tsiolkovsky's fancies were likewise rooted in reality, in mathematically exact calculations of the actual world, and on that basis he made his brilliant guess about what was necessarily going to come into existence. The space flights of the cosmonauts showed how real were Tsiolkovsky's dreams and fancies.
Thus you see that dreams and fantasies are also a reflection of reality and arise only on the basis of it. Reality lends wings to dreams.
It is clear then that materialism not only does not reject dreams and fantasies but, on the contrary, scientifically explains them.
Let us examine another question that often arises when thinking about the problem of the relation between matter and consciousness.
If materialism denies the existence of the soul, does it not also deny such important human qualities as feelings, enthusiasm, passion, i.e., what may be called man's spiritual wealth? We are accustomed to saying, for ex- ample: "How soulfully he plays", or "He put all his soul into the work". What else is there to put if there is no soul? Is sometimes asked. The contemporary French theologian Pierre Bigo writes that materialism "refuses to recognise spiritual values", for it recognises only material values. Is this true? Of course not! It is a slander on materialism. Materialists reject the idea of the soul as a special non-material entity. But they do not deny man's inner, spiritual world. Nor do they deny mans spiritual wealth. It is an inferior writer who does not try to get at the soul c'i the reader, to influence his feelings.
The Soviet Communist Party has always been concerned not merely to multiply material wealth but also to develop the spiritual wealth of Soviet people. People's consciousness cannot be divorced from the conditions in which this consciousness takes shape; we have seen that consciousness reflects life, reality. The Communist Party establishes conditions for bringing out people's finer feelings, for inculcating a high level of consciousness in the builders of communism. The grandeur and beauty of their ideals are dear to the Soviet people. How pitiful, therefore, are the attempts of bourgeois "critics" of Marxism to ascribe to communism neglect of the spiritual, emotional aspects of the human personality. A tell ing refutation of these lying assertions of present-day anti Communists is to be found in the new Programme of the C.P.S.U., every page of which testifies to special care for the education of Soviet people, the builders of communism.
Materialism, therefore, recognises the secondary nature of consciousness but does not deny its important role in man's life. Let us now examine this question in greater detail. The existence of dreams and healthy role flights of fancy is itself a proof that consciousness does not passively perceive the world. In this instance consciousness, as it were, outstrips reality, actively affects it and indicates ways and means of changing it.
Consider, for example, the realisation of the plans outlined by the C.P.S.U. and the Soviet people. Here thought, consciousness, outstrips reality, shows it the way and gives the nation a gigantic creative impulse. Consciousness plays the part of an active mobilising force. Millions of workers take up great causes for the sake of the triumph of communism. It is in this sense that Marx said that when an idea captures the people it becomes a material force. It means that the people, inspired by a great idea, are capable of great deeds. That is how one should understand Lenin's statement that consciousness creates the world.
While reflecting reality, consciousness at the same time is a guide to changing it. Take Marxist-Leninist theory which has become today a powerful material force in the struggle for peace, democracy and socialism.
Idealists considerably over-exaggerate this aspect of human consciousness. They say: since consciousness is active, it is therefore primary, basic; it is consciousness that guides people's actions. They claim that the active nature of human consciousness means the triumph of idealism. But is this so'? The fact that consciousness guides people's actions does not mean that it is primary. On the contrary, all aims, tasks and plans for activity are taken by consciousness from reality, from this activity itself. This has been seen above.
What has been said about the activity of human consciousness helps us to analyse and correctly explain one of the most surprising phenomena of modern industry.
You have heard about computers. They can carry out very complex tasks: translate from one language into another, guide an aeroplane, drive a train and even play chess. They can perform some logical operations that are characteristic of the human brain. They decide when a train has to be slowed down, they "remember" certain operations, etc. It is as if metal were endowed with human thought.
But could a machine be constructed that would wholly replace the human brain? No. It is true that the machine can faultlessly perform the functions for which man has adapt- ed it. It can even discover new facts that its creator did not know. But it will always be merely an auxiliary to the human mind. Without man it is mere "dead metal".
Why is the human brain immeasurably superior to any machine? Because it is the product of social relations. Thought, too, as we have seen, has a social character. The work of the brain is as complicated as these social relations. But no "electronic brain" could "reproduce" man's inner spiritual world, his active nature, his flights of fancy, dreams, the ability to exert his will, the complex world of art. We have examined some of the basic problems of dialectical materialism. To obtain a deeper understanding of them we must have a clear conception of the essence of Marxist materialist dialectics, which is revealed in its laws and categories. These we shall now proceed to study.
1. A reflex is the reaction of the organism to a stimulus from the environment, which takes place with the participation of the nervous system.
2. Marx, Capital, vol. 1, p. 19.