Consciousness is also held to be the result of aggregates of physical and physiological motions or external behaviour. This is tantamount to the materialist theory that consciousness can be a product or a mixture of unconscious elements. External behaviour observed in bodies moved by the nervous system cannot be supposed to be the source of consciousness. Behaviour is what is observed as a function of the psycho-physical organism, and not merely of the body. Behaviour is external, it is an object known; and the observer of the behaviour cannot be its product. It is consciousness that is presupposed even in the observation of the behaviour. What is called behaviour is the visible physical manifestation of the manner in which the internal psyche works through the instrumentality of the body and the nervous system. This controlling system is as much physical as the outer body, and so it cannot be the source of consciousness. The behaviourists think that sensations, perceptions, thoughts, emotions and the like are reducible to physical or physiological reflexes. But they forget that the physical and the physiological phenomena are external to consciousness and cannot be identified with it or considered to be its origin. Behaviour is regulated by physical functions, while the reverse is not always the truth. Though it is true that the appearance of intellect or conscious functions is seen to be invariably concomitant with an observable behaviour of the nervous and the bodily expressions, it does not mean that consciousness is an effect of physical conditions. It is natural that external behaviour should appear simultaneously with a function of consciousness, as the former is governed by the latter, but it cannot be the cause of the latter. It is a wrong application of the scientific method of observation and experiment that has led to the belief that observable behaviour is the cause of all conscious operations. Consciousness is never observed, but is at the root of even the endeavour to conduct the observation or perform the experiment.

Psychoanalysis considers consciousness as only a partial censored expression of the vast reservoir of the unconscious which is the ultimate cause of all individual functions and activities. Intellectual activity is said to be an expression of hidden unconscious impulses. Consciousness and reason are subordinated to unconscious urges, cravings, appetites, all which are expressions of man’s natural biological interests like sex, hunger, the instinct of self-preservation, love for power, etc. The essence of consciousness is thus traced back to the unconscious. The difficulty that the psychoanalyst presents is that even the existence of the unconscious is discovered only by the operations of consciousness. It was already observed that an unconscious cause cannot bring forth a conscious effort, for cause and effect are mutually related. What is not in the cause cannot be present in the effect. If the unconscious is devoid of the element of consciousness, it cannot be the cause of consciousness. It may be considered that the individual consciousness and reason exhibit elements drawn from an unconscious matrix of instinctive urges, but the innermost consciousness that is behind the instinctive operations, even when rationalised, is not the same as the contents of the unconscious. If consciousness were an effect, it would be an object known externally; but we find that it ever remains the knowing subject of which everything else, even the unconscious, stands in the position of an object.

Consciousness is not a mere property, a quality or an attribute of the Self. If consciousness is a quality of the Self, what is the essential nature of the Self? It, then, should be different from consciousness, i.e., an unconscious entity. On such a supposition, we cannot account for the subject-nature of consciousness and the object-nature of all else. An attribute is not identical with the substance in which it inheres, and so the Self would stand apart as an object of consciousness. It is absurd to think that the Self can be an object, for if it were so, there would be no subject to know it. And yet this is what happens when consciousness is considered to be an adjective of the Self. All attempts to give the Self a tinge of objectivity end in failure, for it is impossible to distinguish between consciousness and the Self.

The Atman is different from activity, and has no relation to activity, for the latter is an external relation, and so non-eternal, while the Atman is eternal. There cannot be action without a spatial and temporal existence of its subject, but the Atman is non-spatial and non-temporal. All actions modify their subject, while Atman is not subject to modification. Action can abide in an individual, but not in the Atman. There cannot be action without duality, a distinction between the agent, the action and its purpose, but the Atman is non-dual. The Atman is ever perfect, but action is an indication of imperfection, an effort to overcome an existing defect. The Atman is different from activities like desire, volition, etc., for they are as external and as much in need of the phenomenon of duality as physical actions.

Consciousness cannot be a property of the body, for the latter is its object. Consciousness is not subservient to its own object. The body never becomes the knower; it always remains the known. If consciousness were the essence of the body, then, as the essence of a thing cannot cease to be, there would be no death of the body, or its bereavement from consciousness. It is seen that the body is used as an instrument of action by internal conscious functions which are all illuminated by the Self. Further, on the assumption that consciousness is the essence of the body, there would not be a disintegration of the parts of the body, for consciousness cannot be divided. If it could be divided, a part of it would stand ‘out there,’ as an object capable of being perceived. But we see that this is never done. The body is inert and perishable, and its consciousness is borrowed from the Self through the mind and the senses.

The senses, again, are not conscious by themselves, for they are instruments of knowledge. The senses are objective and only bring about a relation of the subject with the object. An instrument is always used by another different from it. The functions of the senses are diverse. The sensations which they carry have to be synthesised into perceptions and concepts by an intelligent principle different from them. If the senses are to be regarded as the Self, there would be many selves, and no knowledge of the kind ‘I who see, smell and taste, also’ etc. would be possible. Plurality cannot be explained without unity. Even when objects are destroyed and the senses are suspended, there remains the consciousness of one’s having felt externality. Hence consciousness is not the senses. There is the knowledge: ‘I am deaf, I am blind,’ etc., which implies the existence of a common subject relating together the functions of the different senses. One can also imagine that the body and the senses are not, but one cannot think away self-consciousness. It is also observed that in the state of dream the sense-organs do not have their usual activity, and yet one’s consciousness does not cease to be. The Self can never be diversified and changeful like the senses.

The fact of the existence of an immutable consciousness is known from the implications of our experience in the three phenomenal states of waking, dreaming and deep sleep. In the waking state, the individual identifies itself with the physical body and feels: ‘I am the body.’ If a question is put to a person as to who he is, he will normally describe the relative characteristics of his physical personality. This means that he feels his essence and existence to be identical with the visible gross vesture. But this assertion of the oneness of one’s essence and existence with the physical body is contradicted and disproved in dream. The individual in dream exists, and has various kinds of experience. But the physical body then is disconnected from consciousness. If we gently touch the body of a dreaming person, he will not be aware of this, our act of touching him. All his senses are deprived of consciousness when he is not awake. A few particles of sugar placed on the tongue, the organ of taste, of a person who is dreaming will not produce any conscious reaction from him. He will hear no sounds, see no forms, understand nothing. This shows that the real senses, the avenues of the perception of objects, are not the external organs of sense but certain internal forces which dissociate themselves from the physical body when one is in the state of dream. The fact that these forces responsible for the perception of the world are in conjunction with the body in the waking state explains sense-experience in waking life. And their disconnection from the body in the dreaming state accounts for the impossibility of having any physical experience in that state.

Now, is the dreaming person who is differentiated from his physical body in the dreaming state the real person identical with this body, or not? We are forced to believe that we are not in fact the physical body. Else, we would be in eternal conjunction with it, and we should experience it even in dream. But the fact being different we have to conclude that the real person is not identical with the physical body. Not even the dreaming person, nor even the dream-body can be identified with the highest reaches of consciousness. In deep sleep, even the dreaming personality is separated from experience and there it appears to be nothing at all—not even fit to be equated with being. The person seems to be bereft of the value and content of all conscious experience. Everything that is known in the state of dream is cast aside and the personality withdraws itself from all objective conditions.

What, then, is the nature of the person who is the real experiencer of things? What is the ultimate principle underlying life in the state of deep sleep? We have, perforce, to admit, perhaps, that what is experienced in deep sleep is the ultimate reality. But are we prepared to accept this position? Are we conscious in that state? The answer is, no. We seem to be merely a mass of ignorance. Are we, then, ignorance essentially? Perhaps no one would agree with this proposition. Everyone instinctively feels that he is intelligent, not ignorant, not a bundle of stupidity or a bankrupt in understanding. Further, what is the experience which one has when one wakes up from deep sleep? One remembers that one had sound sleep, that one did exist even when fast asleep. How does one know one’s existence in a state where there is no consciousness at all? This is possible due to the subsequent memory which one retains of having slept soundly previous to this conscious state of remembrance. But as remembrance or memory of anything is not possible unless that thing had been the object of one’s conscious experience, we have to conclude that the experience of which we have a memory subsequently was one of consciousness sometime back. In other words, we had in the state of deep sleep conscious experience. But does this not contradict the blatant truth that we had no consciousness whatsoever when we were asleep? Here we are led to a dilemma wherein with one breath we have to hold that we did not have any consciousness and also that we did have it at one and the same time.

We can extricate ourselves from this apparent quandary regarding the nature of consciousness in deep sleep by admitting that we existed as conscious experiencers then, though we did not have any such experience. This has to be admitted, for there is no other way of explaining this baffling predicament. But this absence of the experience of consciousness has to be explained. From the nature of the case we argue that consciousness must have been covered by some obstructing factor in deep sleep, but consciousness as such was never non-existent. If it had been non-existent, we could not have a memory of having slept soundly, i.e., our personality posterior to the state of deep sleep would have been entirely cut off from the preceding state. Consciousness seems to be a continuous element in our life. It persists in all states of experience. Even in swoon it exists. Even if we think that we are dead, it exists. Behind every thought, even the thought of the non-existence of everything, there is consciousness. Something exists. Something persists always. And even the one who denies the existence of all things does exist. Even the nihilist exists. Denial is preceded by the consciousness of denial. This conscious is the ultimate reality. It is the only existence, for it is the sole unchanging being which survives all change, surpasses all that we know, and while everything that we consider our own leaves us at some time or the other, it never deserts us. The essence of the personality and individuality of man is consciousness. This is true existence. This alone can be eternal.

The following detailed account of the nature of Atman as Existence, Consciousness and Bliss is given by Swami Sivananda in his Jnana-Yoga (pp.137-146).