The existence and independence of the spirit can also be adduced as a decisive and convincing proof of life after death. Numerous theories have been put forward by scholars concerning the riddle of the spirit, and the greater becomes the scope of philosophical inquiry and the more carefully use is made of human knowledge, the clearer and more convincing become the proofs for the existence of the spirit and its independence from the body. Of course, we cannot be completely successful in clarifying the quiddity of the spirit, nor can we can lift the veil from the numerous complex mysteries of this eternal entity.
For this reason, the Qur'an depicts the essence of the spirit as an unknowable truth the complete cognition of which lies beyond man's reach. When the Prophet, peace and blessings be upon him and his family, was asked concerning the essence of the spirit, the Qur'an told him to answer as follows: "O Prophet, they ask you concerning the nature of the spirit. Tell them: The spirit is an affair of God, and its essence is unknowable to man. Whatever understanding of it has been given to you is extremely slight" (17:85).
Fourteen centuries have passed since the Qur'an gave this answer. The scope of human knowledge is today very much greater than it was in the time of the Prophet, but very little has been added to this aspect of man's awareness. The essential nature of the spirit still eludes man's grasp, and nobody has been able to clarify it. Just as the Qur'an proclaimed, it remains veiled in a halo of obscurity, and it is highly probable that it will always remain so.
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Henri Bergson, the well-known philosopher, says: "We can conform to Plato and offer a definition of the spirit that is antecedent to experience. We can say that the spirit, being simple, is indivisible, and that because it is indivisible it is also incorruptible, and that it is therefore eternal in its essence.
"For two millennia men have reflected on this concept of Plato, but it has not advanced our knowledge of the spirit in the slightest." (Du Sarchishma-yi Akhlaq va Din, pp. 388-389)
Dr. Chesser, an English scholar, writes: "Some people say that the mechanical operations of our brain form the ego or the self. Others say that it consists of the brain with the addition of a mysterious spark which leaves our bodies at the time of death. As you know, the philosophers have reflected a great deal on the spirit: its nature, its locus in the body, whether it is mortal or eternal, but none of these questions has yet been solved, despite the continuing of efforts of scholars.
"Recently many scholars have decided to study the matter from another point of view by putting the whole question of the spirit aside as too complex and obscure and studying instead the mind or the soul i.e., the totality of man's feelings, beliefs and thoughts." (Rushd va Zindagi, p. 134) Indeed, if one takes into consideration the fruitlessness of all efforts undertaken for understanding the spirit, how can he believe that it contains some mysterious property which compels our submission and veneration?
The Noble Qur'an says the following, in the course of some of its verses concerning the creation of man: "We created man out of pure earth, then We made him into a drop of sperm and lodged him in a safe place. Then We made the sperm into coagulated blood, the coagulated blood into a formless piece of flesh, and the flesh into bones, and finally We clothed the bones in flesh. Thus We brought forth a new creation. Glorified be the perfect power of the Best of creators!" (23:12-14).
"Then God completed the creation of man and inhaled in him of His own spirit and appointed for you eyes, ears, and a heart. How little you men give thanks" (32:9).
"When I complete the outer creation of man and breathe into him of My own spirit, prostrate yourselves before him, 0 angels!" (15:29). These verses describe the successive stages of creation that succeed the coming into being of the drop of sperm, the final result of which is a perfected human body; they indicate that something more valuable and significant is at issue than the creation of a mere corporeal form. They indicate that the infusion of the spirit into man's bodily form constitutes itself a "new creation," which belongs to a category different from the various stages of the evolution of man's bodily form, each of which is necessarily accompanied by the traces and properties of matter. The spirit is a different essence, bearing no similarity to the things created before it. Infused into man's bodily composition, this spirit which God relates to Himself and is thus the closest of all things to Him is independent of the body and separate from it, beyond the reach of matter and all its attributes and properties.
Even the materialists despite all the differences of opinion and ideology that separate them from the followers of religion do not go so far as to deny the existence of something called the spirit. They regard sciences such as psychology and psychiatry as valid, but part company with the theologians and metaphysicians on the existence of a second reality in man that subsists apart from the material body and independently of it; this reality has a nature peculiar to itself and is the source of thought and reflection in man.
This does not mean that body and spirit are two realities that are separate from each other, in the sense of each expressing itself completely independently of the other. They are two realities that are connected to each other while being utterly different in their essences.

Beliefs of the Materialists
The thoughts of the materialists on this topic are based on the assumption that a substance called the spirit does not exist independently of matter. They insist that all the activities of the brain are controlled by the laws of matter and result from physical causes and chemical reactions of the brain cells and nerves.
Our nervous system at all times links our perceptions to a central organ, the brain, and these perceptions in turn give rise to a single and indivisible whole. The phenomena that we associate with the spirit are nothing other than physico-chemical reactions. When the brain cells are exhausted and the reciprocal influence of the bodily organs comes to an end, so that the cells cease motion and reproduction, nothing is left of the essence of man save a material form. It is therefore impossible to accept any kind of spiritual immortality or the existence of an autonomous, independent, supranatural entity in man, for both the first appearance and the subsistence of the "spirit" were caused by a spatially and temporally determined connection.
Here the materialist and religious schools of thought part company decisively.
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If we accept the claims of the materialists, man will be like a machine, put together from different components and parts, and all traces of life and thought in him terminate utterly once the reciprocal influence of his material components comes to an end. Such an interpretation of the matter fails to do justice either to the reality of the human spirit or to that of man himself.
It is true that the body submits involuntarily to physiological law, but this observable reality does not lead to the conclusion that man is in his entirety chained to the laws of matter with the force of a mathematical equation. There is certainly a close connection between the phenomena of the spirit and the cells of the brain; without having at its disposition a certain number of instruments and tools, the spirit cannot undertake any activity at all in this world. The brain cells, the nerves, and the chemical reactions of the brain, all count as the tools of the spirit by means of which it accomplishes its activity.
It must be asked whether not only the spirit but also its manifestations such as will, determination, perception and so forth, are realities independent of matter, or are themselves entirely material, dependent upon it in all conditions and circumstances. By way of analogy it may be asked if we conduct a long-distance conversation by means of the telephone, whether we are the real hearers or the telephone receiver?
Is the telephone simply the instrument by means of which we hear the soundwaves, or is it the true and actual hearer?
Matters are the same with respect to the brain. The brain cells are the tool of the spirit, not its creator. All that the proofs put forward by the materialists establish is that there is indeed a link between man's perceptions and his brain cells, not that the brain itself is engaged in perception. In any event, no theologian maintains that thought takes place outside the sphere of the brain cells.
The effects and necessary attributes of matter must inevitably be found in all material beings; it is unacceptable that the properties of matter should be absent from any material entity. If therefore an entity is lacking in the effects and properties of matter, and the effects and properties it does possess do not coincide with those of matter, there can be no doubt that entity in question is not material.
As an objective reality, man is the source of a series of distinctive effects which inseparably accompany his objective existence. Certain of the realities that prevail in human existence can be explained in terms of material criteria, but others do not accord with the properties of matter and cannot be weighed by its criteria.
Here we encounter the fact that in man, in addition to his material composition, an entity exists that is separate from matter and superior to it; it is the source of various forms of perception that belong to a different category than matter. In fact, each of the perceptions of man, together with its special properties and attributes, is in itself a clear proof and indication of the existence in man of an entity other than his corporeal composition.
If those perceptions were to be the effect of man's physical makeup, his particular bodily composition, if perception and reflection, hearing and seeing, were simply a function of his nerves, they should be explicable in terms of the laws governing his nervous system and his brain cells. However, they are not. Let us assume that seeing is the formation of an image in the brain; still the question arises of who sees and perceives, who is the author of the act?
Again, if we assume that man is nothing other than a certain type of material composition in a certain part of which an image has been formed again we ask whether the one that sees and perceives is the totality of the bodily composition or only that small sector of it in which the image has been formed?
The totality of the material composition cannot see and perceive the image that has been formed in a small part of the whole, and it is also impossible for that part to see and perceive; can a material thing see and perceive the images that are formed in the thing itself? Were it so, a painting or a piece of paper would be able to see and perceive the paintings that the painter has executed on them.
Although scientists have been able to establish empirically that there is a link between perception and consciousness on the one hand and chemical reactions in the brain on the other hand, the only conclusion they can draw is that the nervous system and the brain play a decisive role in the occurrence of perception and various psychological states. The experiments these scientists carry out do not at all permit the conclusion that the essence of the spirit is equivalent to the activity of these instruments of perception or to physical and chemical effects. Finally, proving that the link exists is in no way sufficient to defining the distinctive states and properties of perception and awareness.
To draw an analogy, the spirit is like the electric power required to set a machine in motion. Whenever the power is cut off, the whole of the machine comes face to face with a kind of death, even though its individual components may be quite sound and unimpaired.
Similarly, when man dies the link between his spirit and his body is severed, but the severance does not mean the destruction and death of the spirit. If our telephone, radio or television stops working, we lose our means of communication, and we no longer hear distant sounds or see distant images. Those sounds and images exist everywhere, but we do not see them or hear them; we become aware of them only when our means of communication is provided by the telephone, radio or television.
Sounds and images subsist, then, independently and separately from the instruments required for their perception. Likewise the spirit of man is independent of the body while being linked to it, and it does not perish with the death of the body.

The Particular Properties of Perception
We know that a basic difference separates the functioning of the brain from that of the various parts of the body, all of which have in one sense roughly similar functions. The kidneys, for example, are compounded as a result of various physical and chemical activities; their function is related entirely to the inner organs of man's body. By contrast, the phenomena of the spirit relate to the external world that lies outside our personal existence. It is obvious that external world has no ingress to our personal existence; it is on the contrary we who must attempt to comprehend it in order to become aware of external existents, a task of which our brain cells are incapable. Like other dimensions of our body, the brain cells receive effects from the external world but they cannot gain awareness of the nature of matters in the external world. Were that not the case, we ought to be able to perceive the external world with our stomach and lungs. The special nature of our perceptions tells us, then, that another entity rules over our beings.
Let us raise another question at this point: who is it that judges the images that are formed in our brain?
If we meet two people, one of them old and the other young, and images of both of them are formed in our brain, we compare the two images and decide which person is old and which is young.
Several factors are at issue in this decision. First, the seeing and perceiving of the two images that are formed in the brain. Second, the comparison of the two images and the identity of the person that makes the comparison. With respect to this second point, it may be asked how man acquires the power to compare if he consists of nothing more than a series of bodily compounds. Third, the perception of the old man as being more aged than the young man, which follows on the comparison of the two images; here, the perceiver must also establish a relationship. If man consisted exclusively of his bodily form and lacked any non-material dimension, he would be totally unable to establish such a relationship. For a relationship does not have any sensory shape or form that can express itself as an image; we cannot possibly explain the establishment of a relationship through recourse to the criteria of matter.
The fourth issue is perceiving one of the two men as being older than the other. Again we can say that if man consisted only of his physical being, he would not be able to determine which of the two images that have formed in his mind represented an older person.
When we distinguish truth from falsehood, when we appreciate beauty and separate it from ugliness, we are dealing with matters that are external to us and judging them in accordance with certain criteria. The existence within us of a capacity to distinguish truth from falsehood, right from wrong, to measure phenomena external to us by criteria of our own, demonstrates in itself the independence of the spirit. Judgement and discernment are beyond the capacity of the nervous system; they derive exclusively from the operation of thought and the activity of the mind, and cannot be explained in sensory terms.
The unseen light within our inner beings that permits us to distinguish good from evil, beauty from ugliness, right from wrong, is an absolute reality and is none other than our eternal spirit. All temporal occurrences revolve around it, for it is itself an immutable and indivisible pivot of all things.
One of the precious properties of man is his ability to perceive universals, which permits him, after analyzing his experience and sensory perceptions to deduce permanent, fixed and unchanging universals from the particulars that he has observed. With his sense of touch, for example, man can feel the weight of iron. After repeating this sensory perception, he engages in analysis and reaches the universal conclusion that iron is heavy.
It is thus that man deduces the universal laws and realities that exist in all the particular instances, by analyzing the particulars and abstracting them from their temporal and spatial contexts. These universals form an important part of man's knowledge, for they are the source for his conclusions and judgements.
Were we to regard man as consisting exclusively of his bodily form and to deny the existence of an autonomous spirit, we could not explain the knowledge of universals in any acceptable way, for we would confront the problem of how the processes of analysis or abstraction to which man's sensory experiences and perceptions are subjected take place. How could the physical composition of our bodily form undertake the tasks of abstraction and the deduction of universal rules from particular instances?
If we regarded the deduction of universals from particulars as a reactive function of matter, precisely how would it take place? How can we depict, as a material process, the perception of a universal principle? When we perceive a universal principle, we are in fact perceiving an objective reality that is free of all material, temporal and spatial characteristics; it is the existential effect of an entity superior to matter. If despite all this, some people wish to insist on a materialistic explanation of the matter, their explanation must count as unrealistic, baseless and far removed from the truth.

The Unity of the Personality
Another matter which can help us to appreciate the autonomy of the spirit is the unity of the human personality which covers the entirety of man's life. There can be no doubt that man's knowledge of himself is different from his knowledge of beings external to himself. His knowledge of those beings occurs by means of a reflection of them being traced in his mind; it is thus that we gain the kind of knowledge that is known as "acquired knowledge." As for the knowledge that man gains of his own self, it does not come about through the occurrence of an image in his mind; it is present with him at all times and is inseparable from him, being known therefore as "present knowledge."
This constant presence, which is not subject to change or diminution, and possesses stability and permanence in its ability to feel and gain awareness, represents the clearest and most evidential form of human knowledge.
The entity which is exempt from change and impermanence (these being the attributes of all external reality), which controls and rules the material body, which is not subject to biological determinism, which expresses itself as this entity is one and the same from the first stages of life until its last moments. Man enjoys permanence by virtue of the permanence of this entity. Its ontological level is infinitely higher than that of matter and material beings, for the unity of the human personality is preserved throughout all the stages of change an individual undergoes in his lifetime.
Can this unchanging entity in any way be ascribed to or regarded as identical with the brain cells?
The contents of the brain cells completely change during the life of an individual through the absorption of matter external to themselves and the transformation of it into energy. New material takes the place of material that dissolves. In fact, every living creature may be re-created several times over in the course of his life as a result of the ceaseless changes of his molecules and the particles of his body.
Were we to be composed only of matter and were there to be no invisible force controlling the mass of our cells and the structure or our bodies, given the fact that the content of our nervous system and our brains changes several times over in the course of, say, fifty years, and the entirety of our physical form undergoes various fundamental changes, the reality of our being would be entirely controlled by the attributes of matter and we would no longer be the same distinctive person that we were last year. We know, however, that there is a single stable and immutable reality which comprises our personality and assures its unity and distinctiveness.
That stable entity which exists in man is like the reflection of the moon or the sun, shining night and day on the water. Although the waves are in constant motion and flux, one wave advancing to have its place taken by another, the reflection of the light of the moon or the sun is stable and uniform: Time and again the water has changed in the stream, But the light of the moon and the stars maintains its gleam.
The stable and immutable spirit keeps shining down on the river of the body, just like the light of the moon and the sun. Although the cells and molecules of the body perish, the slightest change does not occur in the essential personality of man.
Everyone can perceive the existence within himself of a spirit that is both independent of the body and possesses a form of existence totally different from that of the body. Everyone is aware within himself of an identity that is autonomous, continuous, constantly present, and stands in contrast to his material being which changes every day.
One cannot possibly regard an entity that thus dominates the body and unlike the body is immune to diminution as being the product of matter or subordinate to its rules. Any supposition of this type cannot explain anything concerning the true nature of man. Cressy Morrison writes: "What is certain is that the creation of this world was not the outcome of accident or chance, because the entire order of the world revolves around specific laws.
"The appearance among the animals of man, endowed with thought and intelligence, is too mysterious and too significant for us to imagine it to be the result of material processes, without the hand of a Creator being involved. If this is not the case man must be like a mechanical instrument requiring someone also to set him to work. But then whose hand would it be that sets him in motion?
"Until now, science has not been able to provide any explanation of who this operator might be, only one thing is certain that the operator cannot be a material compound.
"We have progressed only so far as to imagine God bestowing a flash of His own knowledge on our existence. Man is still passing through his infancy in the understanding of creation and is just beginning to understand the existence of the spirit; he is gradually becoming aware of this heavenly gift and its eternal, everlasting character." (Raz-i Afarinish-i Insan, pp. 180-181)
If the manifestations of the spirit are simply part of the effect and properties of the body, the outcome of the activities of the brain, or reducible to the total functions of the nervous system, how can we analyze and explain the persistence of the human personality? It is, after all entirely natural to suppose that an entity which refuses to submit to the laws of matter should be permanent and everlasting.
The explanation offered by certain materialists to the effect that the self is relative and that it undergoes change and development while possessing stability, is more of a poetic than a scientific nature; it cannot in any way explain the unity preserved by the human personality throughout life. For this incorrect theory arises from a theory of man which is even more erroneous; it would imply that "I am not now that man that I previously was; I am someone who has taken his place but I somehow fancy that I am the same person as before. In addition, these imaginings are my act and I am their source; it is not that my self comprises the varied and ever-changing concepts that take form in my mind."