Year : 2014 | Volume
: 2 | Issue : 1 | Page : 9--14
Psi, consciousness, and reality
Thaiyar M Srinivasan
Department of Yoga and Physical Sciences, Swami Vivekananda Yoga Anusandhana Samsthana, Bangalore, Karnataka, India
Thaiyar M Srinivasan
81 Astalakshmi Nagar, 3rd Street, Valasai, Chennai - 600 087, Tamil Nadu
Parapsychology and psychic phenomena are looked open with great deal of suspicion. However, siddhis have been discussed in details in Yoga Sutras and practitioners of Yoga have glimpsed these siddhis at least in passing. Further, in India, one could always come across siddhas-people who exhibit siddhis-of various colors and hues, so one is not intimidated or confused regarding this aspect of Yogic practices. There have been attempts to link stages of consciousness to psychic competency and to siddhis. While consciousness is not defined adequately in literature, the nature of reality is defined as related to sensory world only. Psi research opens up possibilities of extending both the understanding of consciousness and the nature of reality, while Yogic literature and Vedanta could throw much clarity to both these through workable hypothesis. This paper attempts to present these ideas and proposes a model for Turiya Consciousness (TC) or Ultimate Reality that ancient wisdom refers to in Vedanta.
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Srinivasan TM. Psi, consciousness, and reality.Int J Yoga - Philosop Psychol Parapsychol 2014;2:9-14
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Srinivasan TM. Psi, consciousness, and reality. Int J Yoga - Philosop Psychol Parapsychol [serial online] 2014 [cited 2023 Jun 10 ];2:9-14
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Sciences such as physics and chemistry are thought to be hard sciences, while psychology and social sciences are termed as soft sciences. The Newtonian world was very deterministic and projected a world in what seems to be unambiguous terms. It was thought that experiments in hard sciences result in repeatable and consistent results that are space and time independent. Soft sciences on the other hand, are so termed since the outcome of experiments is extremely variable and not necessarily repeatable. Take the instance of determining the personality (extrovert or introvert) of an individual; it is likely the result of tests could depend on the mood, amount of sleep and stress experienced the previous day, relationship at work and home, etc., which could all be transitory. In physics also, in the microscopic world of quanta, electrons do not behave with Newtonian certainty. We can only predict the outcome of these experiments in probabilistic terms. Thus, we find in the physics of microscopic world as well as in psychology and related sciences, we could only sketch the likelihood of outcomes. This is true in medical sciences also; we can say a drug could act in a particular way in many patients, but not necessarily in all patients. The dynamism of the biological system (including the brain and mind) makes measurements and outcome uncertain.
The two disparate cultures of humanities and sciences that Snow talked eloquently about  have now pervaded science itself-in addition to the schism between humanities and sciences! Statistics rule both the hard and the soft sciences to tease out the minute details from nature. This fortunately provides immense possibilities in both life sciences and mind sciences. Studying these sciences, one is amazed at the complexity and diversity of expressions of living systems. Many have voiced that mind is the creator and mind is also the destroyer; mind creates what we experience and it could be the slayer of both the world and of itself. We shall look into some aspects of the excursions of mind later in the paper.
Parapsychology as the name implies, goes beyond the pale of psychology. Psychology is the science of mind; it is the study of the many modes of activity of the mind and understanding mind related problems. If these problems are persistent, it could give rise to physical ill-health and hence recognizing the problems could lead to healing and cure. Parapsychology is the study of psychic phenomena wherein exchange of information is through channels other than the ways we are normally used to. For example, feeling uneasy about an event and subsequent occurrence of that event is an experience that all of us go through some time or other. Such feelings are not mediated by any known physical fields or phenomena.
As mentioned above, mind has capabilities that are very difficult to fathom and even more intricate to study. In the third Pada or Chapter of Yoga Sutras, Sage Patanjali has enumerated various siddhis or occult powers that are displayed by a Yogi as he/she practices samyama. Samyama is the practice of dharana, dhyana, and samadhi on any object of focus. In brief, dharana is focusing on any object of interest, dhyana is continuous thought on that object, and samadhi is to become one with the characteristics of the object. Samyama could be on the life giving sun, the moon, and the stars or it could be on the mind itself and its many manifestations. All of us have gone through the experience of premonition or forewarning of an event especially of something or someone we are very much involved with. There are other 'vagaries' of the mind that are also of interest. Here is a brief definition of the 'mind play' that we go through in our life.
Psychic phenomena go by the general name psi (Greek letter y), an unknown entity related to unfathomable activities of the mind.  The anomalies constituting the working of the mind are classified into three broad areas. They are: 1) ESP or extra sensory perception; 2) PK or psychokinesis, and 3) Precognition. Apparitions and past life experiences are also appended as possible ESP related events. All these are subjected to numerous experiments over a hundred years in the western world. It is interesting to note that the Society for Psychical Research was started in England over 130 years ago with the main objective of investigating some of the above phenomena. The eastern world is used to people with these extraordinary expressions; however scientific investigations (other than direct observation) in the east are of recent origin. Let us look into the above three categories of psi phenomena in more detail.
ESP is a term coined by the famous researcher J.B. Rhine in early 20 th century, who studied and analyzed enormous amount of data on the ability of people who could perform certain extraordinary mental tasks. As mentioned earlier, ESP refers to three types of extra sensory abilities of telepathy, clairvoyance, and precognition. Telepathy is the ability of communication between one or more minds directly without any known access through sensory channels. Precognition, as the word indicates, is information received (in the mind) regarding a future event. It includes two components, namely, premonition (of a great loss or gain) and presentiment which is being aware of a future emotion. The last may be considered as self-reflexive mind finding itself in a mood that is yet to come! Clairvoyance is the ability to see at a distance (over thousands of kilometers) again without the use of normal channels of communication. It is also called remote viewing. Lastly, PK is examples of mind-matter interactions, whereby mind is able to move or exchange energy with matter. This last may be of importance in cases of healing.
Since psi research has been around for a while, it is fruitful to look at a model proposed for psi competency. Hypothesis of Directional Intention is a representation that allows the mind to attend to incidences of immediate concern or orient away from it. Thus there is an unconsciousness intention of the mind for orienting or not towards an event. Cognitive closure is a situation in which one desires to bring to conclusion an experience which could end in unconscious selection and storing of the experience through unconventional thinking. These two aspects of the mind are integrated in proposing a model for psi experience. When there is no cognitive closure, then one is in suspended animation, as it were, and this seems to be conducive for psi competence.
A model known as First Sight model is proposed to understand the subliminal and preconscious information that co-mingle to provide psi competency. James C. Carpenter, a prominent researcher in this area has this to say: "In terms of the First Sight model, one would say that a person's tendency to make positive use of preconscious information for whatever reason will be expressed with extrasensory and subliminal sensory information alike; whereas, a tendency to avoid such material and express it subtractively, will tend to be shown with both as well" [3, p. 79].
There are experiments to test this hypothesis wherein changing the subliminal stimuli affectively changes the outcome of preconscious processing and this in its turn influence psi response. Moreover, preconscious processing and psi interact to further strengthen the model. Familiar and non-threatening material should, according to this model, produce a strong psi response; and this has also been found to be true in many experiments. Studies related to learning and memory in psi tasks, creativity, hypnosis, etc., have indicated the usefulness of this model.
The above model is primarily a memory/mind based one and is useful in assessing psi ability in people. We often hear the phrase, "Guess if you do not remember"; this implies the answers are produced with the help of subliminal and unconscious processes and often turn out to be correct, if unbiased. However, other areas of psi may require different models to work with. For example, in telepathy and telekinesis, mind/mind and mind/matter interactions are under investigation; here, other models may be required for understanding the interactions.
In telepathy, for example, there seems to be a direct connection between two minds which are able to exchange information. At least, one mind retrieves information that is embedded in another mind. The basic assumption in physics is that psychophysiological phenomena confine themselves within the body without any extension to the outer world. Hence the initial reaction to psi research is that it cannot exist. However, many carefully performed experiments have provided a solid foundation for action at a distance, even for physiological phenomena. While known physical fields such as electromagnetic and gravitational fail to account for these effects, there are proposals for new types of fields-both physical and nonphysical-that could account for psi. Dr. David Bohm has formulated a new vision of 'quantum interconnectedness' and it is possible to explain mind/mind and mind/matter connections. 
Thus, there are attempts to introduce new types of forces that could explain the observed effects. However, these forces are not generated or manipulated in the laboratories suggesting that they may be confined to biological systems only and not necessarily available in non-life systems. These studies could lead one to define life itself in a more consistent manner than hitherto possible. Thus, study of any science, when followed to its logical conclusion, could give us a new vision of life, health, and consciousness.
Sensory Deprivation and Psychic Phenomena
It is known from Patanjali's Yoga Sutras, that a focused mind is a prerequisite to extrasensory knowledge. Indeed many sutras deal with samyama, a focused mind which is receptive to PSI when all other sensory inputs are subdued. In psychic research, on the contrary, a sensory deprivation is created through mechanical means such as putting the person under investigation in an isolation mode. This goes by the name Ganzfield ('ganz' in German means 'entire'). This isolation method takes many means: The eyes are covered with translucent material and kept closed; the ears receive 'white noise' through speakers which is similar to an off-station radio noise. When a person is in this state of isolation for a short time, say a few minutes, he/she becomes accustomed to this isolation and with no other disturbing stimulus, the brain seems to get into a 'psi receptive mode'. Normally, even at this stage, the receiver often reports visual and auditory experiences that are unusual. In a typical experiment, the sender is sent to a remote location in the same building or elsewhere and is presented with computer selected random images in sequence. Normally, four target images are chosen for the sender to transmit mentally to the receiver; after the experiment, the receiver is shown the four possible images and asked to rate the four images in order of possible target sent. If the correct target is selected by the receiver, it is termed a 'hit'; if not, it is a 'miss'. With four cards, the normal hit rate (without any psychic overtones) is 25%. If the hit rate is significantly higher than this, then somehow information exchange has taken place between the sender and the receiver.
The conclusion after a large number of trials is that indeed mind-mind interaction and exchange of information is possible. When the normal sensory disturbance is removed as in Ganzfield trials, it is easier to achieve these states of mental transference of information. Another way of removing or eliminating the 'mind-noise' is through samyama; this is a three pronged way of practicing dharana, dhyana, and samadhi on particular aspects of the physical world. For example, it is said in the sutras  with samyama on thoughts in one's mind it is possible to know the thoughts in others' minds. The mechanism of thought reading could be postulated as follows. Prana is the link between the mind and the body in each individual. Prana is also present everywhere in the physical universe. If we can access the pranic field, it is possible to understand its contact with any other mind since prana is present there also. Thus, samyama with a quite mind and focused thought could unravel the thoughts in other people's mind.
It should be noted that samyama and Ganzfield are not equivalent. In samyama on any object or event, one is in a state of dharana; dhyana; and finally, samadhi on that object. This samadhi, achieved after the first two states, is one of complete absorbance in the object of concentration and with focused awareness. In Ganzfield on the other hand, one is deprived of all external noise to the brain and the brain is quiet and receptive. During samyama, one has already controlled the vagaries of the mind and a focus on the object or intention is achieved. With intense practice, complete knowledge of the object is acquired. This knowledge could be physical such as the way an object is constructed, the materials used, etc. It could also be psychological, such as memory, analysis, and synthesis that is proceeding in another mind. In summary then, Ganzfield is one of quiet receptivity; whereas, samyama is actively seeking a goal through a focused mind.
It is important to realize that samyama per se will not lead a person to the highest levels of consciousness. In other words, a quiet and pointed mind does not reveal Brahman or Turiya Consciousness (TC) or Unity Consciousness as it is sometimes designated. These siddhis are obstacles to samadhi and are acquired when citta is fluctuating [5, p. 277]. It should be noted that samyama is still with respect to mind functioning-though focused and circumscribed in extent-and hence, is not conducive to states of higher samadhi.
As we proceed in samyama, subtle changes in citta (usually translated as mind) are perceived. They are described as samadhi parinama, ekagrata parinama, and nirodha parinama. As citta pierces through subtle levels in three components of property, characteristic, and condition of the citta taking subtle projections of the world and contents of the citta itself [5, pp. 238-47]. The above three are designated as suppression, tranquility and transformation of citta. All samyama are related to sabija, a state of citta with a seed (of thought) still keeping the mind busy within a limited area of activity, which is required for achieving samyama and consequent siddhis. It is important to note that these are still modifications of citta; not its quiescence or its annihilation.
Since citta by itself is not sentient and since citta is vacillating all the time, it is postulated that there should be something that is a plenum which does not change. This principle is called dharmi or substratum or simply Purusha in Yoga [5, p. 248]. This is the same as Brahman of the Vedantic literature. It is Purusha that has sentience, it does not change while the whole world changes; Purusha is the ultimate observer of all events both within oneself and in the entire universe. We call this Brahman or just real since it does not undergo any change; and the world with all material things that change are termed maya meaning measurable. The changeless cannot be measured since it is uniform and most subtle both in time and space. Any measurement is with respect to a reference and such reference is not possible for measuring Brahman since it is space and time invariant. Thus, it is said to be beyond the senses, mind, and other evolutes of the material world. We shall see how to understand this consciousness in a way that is possible to communicate with one another.
Consciousness and Reality
The word consciousness is unfortunately loaded with many definitions; these range from a clinical classification of interacting with the environment to states of samadhi as mentioned in Yoga Sutras. However, it is necessary to formulate a consistent definition of consciousness. Since the word is already in extensive use, an alternate word could be Turiya Consciousness (TC). Though definition of Turiya itself is difficult, this word is still preferred since the uniqueness of this state of consciousness could be of interest. Turiya is defined as the 'fourth state of consciousness, the unmanifested state of Purusha, the eternal principle' [5, p. 396]. This is the Ultimate Reality that the scriptures talk about. As this is not discursive, a description of this state is not possible. Reality is in this way different from reality that science talks about. In sciences, reality is taken to mean all that we see and hear around us. In other words, reality is just the world that we interact with. In the Vedantic concept, reality is the eternal driving principle that is a conscious awareness in all we see around us. This is all pervasive and eternal consciousness that is the supreme reality that scriptures talk about.
Let us first look into a modern seer who has written about this TC from an intuitive and discursive point; these are the writings of Dr. David Bohm. To Bohm, implicate order is the most fundamental aspect out of which the entire physical world "relevates", or is lifted up. He says: "We propose that a new notion of order is involved here, which we called implicate order (from a Latin root meaning to 'enfold' or 'to fold inward'). In terms of the implicate order one may say that everything is enfolded into everything. This contrasts with the explicate order now dominant in physics in which things are unfolded in the sense that each thing lies in its own particular region of space (and time) and outside the regions belonging to other things" [4, p. 177].
Dr. Bohm then turns his attention to matter and consciousness: "It follows, then, that the explicate and manifest order of consciousness is not ultimately distinct from that of matter in general. Fundamentally these are essentially different aspects of the one overall order. This explains a basic fact that we have pointed out earlier, that the explicate order of matter in general is also in essence the sensuous explicate order that is presented in consciousness in ordinary experience" [4, p. 208].
Not only in this respect but, as we have seen in a wide range of other important respects also, consciousness and matter in general are basically of the same order (i.e. the implicate order as a whole). This explanation of consciousness is related to brain function, and to memory consolidation and retrieval. Again, at this level, it is possible to postulate that matter (of the brain) and its function (as consciousness) are interdependent and may not be separated. While Bohm expects an implicate order in the explicate world of matter and consciousness, he does not define it in any particular way.
Summarizing the contributions of Dr. Bohm in the area of New Physics, Fritjof Capra has the following to say: "To express the essentially dynamic nature of reality at this level he (Dr. Bohm) has coined the term 'holomovement'. In his view the holomovement is a dynamic phenomenon out of which all forms of the material universe flows. The aim of his approach is to study the order enfolded in this holomovement, not by dealing with the structure of objects, but rather with the structure of movement, thus taking into account both the unity and the dynamic nature of the universe. To understand the implicate order, Bohm has found it necessary to regard consciousness as an essential feature of the holomovement and to take it into account explicitly in his theory. He sees mind and matter as being interdependent and correlated, but not causally connected. They are mutually enfolding projections of a higher reality which is neither matter nor consciousness. The ground from which the unfoldment occurs is the plenum on which the drama of unfoldment of consciousness takes place". 
Without defining the ground itself (perhaps due to very good reasons), Bohm says: "Our overall approach has thus brought together questions of the nature of cosmos, of matter in general, of life, and of consciousness. All of these have been considered to be projections of a common ground. This we may call the ground of all that is, at least in so far as this may be sensed and known by us, in our present phase of unfoldment of consciousness" [4, p. 212].
Dr. Bohm has spent considerable time with Sri Jiddu Krishnamurthy, the renowned Indian philosopher and discussed many intricate details of consciousness and its manifestation in the physical world. Thus, Dr. Bohm's view of implicate order is again referring to a plenum of order that the Indian texts refer to as Brahman and as TC. It is said to be unthinkable and unspeakable (anirvachaneya). It cannot be circumscribed, discussed, and taken asunder for analysis. Thus, a model for this TC should be different to the physical and psychological models we normally build and work with in sciences, either hard or soft. Prof. Chettimattam has written regarding this in his book in a succinct manner as follows:  "The right way therefore to understand consciousness is to make use of a procedure, as it were, in the reverse gear; in other words to make use of a method of approach that will be the opposite of what is employed in dealing with objects. The object is constituted in our knowledge through affirmation and construction; consciousness is realized by negation and abstraction. The object is built by addition and synthesis; consciousness is reached through elimination and detachment".
The ideas of negation and abstraction are summarized in the famous quote from the scriptures of India as 'neti, neti'; not this, not this. In other words, seeking to understand TC through the sensory world of experience is not possible. One needs to follow the paths prescribed in transcending the workings of the mind so one obtains a glimpse, as it were, of TC.
Perhaps the 'Ground' that Bohm talks about in the above quote may be considered as something that is beyond the phenomenal world which we sense in our interactions around us. Let us call this reality. This reality is the background from which all of the physical worlds arise. This is the 'screen' that one of the great sages of India, Sri Ramana Maharishi, refers to in his teachings: "Which is the screen and which, the paintings? The Self is the screen, and the body and the world are the paintings. And what one needs to do to become aware of the Self is to erase the paintings". 
This is the reality we are discussing now. The body and the world referred to above are the evolutes of that reality; other evolutes include the mind, ego, and all else that we see around us. As indicated earlier, this reality is beyond space and time, not localized, not divisible into parts, indeed, and not even measurable. A doubt might arise why this is not measurable. All measurements are ultimately by the mind. Mind is bound in space and time; thus, measurement of a thing beyond space and time is not possible with a thing (mind) that is bound in these. Moreover, measurement of the characteristics of an object is possible only if there is a difference between itself and the surroundings. For example, a white dot painted on a white wall cannot be perceived. If reality is unchanging in time and space, then it cannot be observed, however subtle the measurement. Thus, even understanding implies using the tools of the mind and hence, reality is beyond comprehension. Thus the saying "He who talks does not know; he who knows, does not talk". Lao-tzu, in the 4 th century, B.C.E. wrote of this: "The Tao which can be expressed in words is not the unchangeable Tao; for, if a name be named it is not the unchangeable name. Without a name it is the beginning of Heaven and Earth". 
A Model for Turiya Consciousness
The postulates of four modes of awareness presented in the Indian scriptures are of interest here. The first two are related to one's experiences of the sensory world in both waking and dream awareness. The third is deep sleep wherein the person is not aware of this state; however, on waking up he/she describes it as a restful and contented sleep. Further, there is no need for the person to describe the state he was in; for, all of us have the experience of this deep, restful state; in fact, all of us hope to be in that state of restfulness while asleep. However, the point to note is that while in that state of complete rest and peace, we are not aware of that state. Only on waking we are able to describe it. In samadhi state however, we are experiencing that peace as we are in deep dhyana. Deep sleep is thus termed 'jada samadhi', lifeless samadhi!
Now examining TC, it is possible to propose a way to understand this through the analogy of a hologram. A laser produces a very coherent beam of light and this is used to make a hologram. The laser light is made to shine on an object whose hologram we want to create. The reflected light from the object is made to interact with a part of the original laser beam and the resultant beam of light is then captured in a photographic plate. We all know the property of a hologram. It turns out to be a three-dimensional view of the object under study. Further, and this is exiting, if we cut out a small portion of this hologram and shine the same original laser beam on the piece, we are still able to see the entire object! Thus, the information of the object is represented in every little piece of the photograph. Hence, this goes by the name hologram.
In a similar manner, we may understand the role of TC in experiencing the external world. This TC or the field of Atma inundates the entire body. A reflected part from an external object is registered by the mind (which, by the way has the field of Consciousness bathing it too). This is the 'awake mode', namely, mind is aware of the external world. In the dream mode, the external object is not there; however, the mind experiences its own contents and the manipulations thereof to experience dreams. The most interesting, however, is the dreamless sleep wherein the mind itself is dormant. We still experience this state since, on waking up, we say "I had a sound sleep". Now, the question to ask is: "Who is it that had good sleep?" The mind is in a state of laya or quiescence; what remains is only the Atma; this ineffable presence is the only entity present at that moment. In the hologram example, when no object is illumined, the light of laser is still captured on the photographic plate. By examining the plate, we see no interaction between the object reflected and the original beams; we see only the light of the laser beam. Similarly, waking up from a dreamless sleep, we have a light of understanding, as it were, that shines forth and now we may say, "I had a sound sleep".
Is there any physiological basis for this model? As we have seen a laser-like radiation inundates the entire body (including the brain and all cells) and this is the one that is designated as TC. This is always present as long as the person is alive. Its interaction with the body gives a holographic memory to all cells and to the brain too. In a recent paper, the authors have this to say: "Citing research in consciousness, quantum physics, biophysics, and cosmology, we propose the collective amplification of quantum effects as the basis for scientifically describing Kundalini awakening and higher order, emergent phenomena of Unity Consciousness. We postulate that bundles of fibers (neural cells), each containing numerous microtubule "lasers" acting in unison, collectively result in a massive surge of light energy in the brain" [10, p. 267]. This paper argues in a convincing way, that quantum phenomena within the body gives rise to higher consciousness, including Unity Consciousness, as the authors call this TC. Though the scientific community is slow in accepting some of these ideas, it could be postulated that most of the body mechanics and control go through propagation of subtle energies with laser like communications that are postulated in acupuncture activity.
Hence, in the above model presented in this paper, TC emerges as an illuminating principle. It illumines the mind/body as it does the entire universe. When the individual consciousness decouples from the physical field (body), then consciousness is lost and so is sentience. The physical body goes through what we term death.
In this paper, it is seen that psi, consciousness, and reality are all interlinked, though not equivalent. Siddhis that Yoga talk about are the result of intense tapas (austerities) and are not conducive to higher levels of samadhi. If one wants to realize the ultimate truth, then siddhis should be bypassed without much attention. They are just sign posts to tell the practitioner that all is well with the practices! To understand reality we need to become that itself. The impediment to this is the vagaries of the mind; there are two ways of transcending the vagaries: laya (suppression) and vina¯sa (dissolution of the mind itself). Sri Ramana Maharsi, in one of his rare compositions says that mind suppressed will project itself again, while the mind dissolved will never able to influence the person again. In other words, the latter person becomes a true observer, of his own body (that might deteriorate and die), his own mind and the transformations that go on all the time around oneself. This then is the ultimate stage for a practicing Yogi and as Bhagavad Gita says, for such a person, there is nothing more to be done for transcendence. He has achieved perfection, one with Brahman. The byproducts of siddhis could be had any time for him and the entire universe is just a play field for such a person.
|1||Snow CP. The two cultures. Cambridge: Cambridge University Press; 1998.|
|2||Radin D. The consciousness universe: The scientific truth of psychic phenomena. New York: Harper Collins Publishers; 1997.|
|3||Carpenter JC. First sight: Elaborations and implications of a model of psi and the mind. In: Rao KR, editor. Yoga and Parapsychology, Experimental Research and Theoretical Studies. Delhi: Motilal Banarsidas; 2010. p. 71-123.|
|4||Bohm D. Wholeness and implicate order. London: Rutledge and Paul; 1980.|
|5||Saraswati SS. Four Chapters on Freedom. Munger: Yoga Publications Trust; 2002. p. 254.|
|6||Capra F. The turning point. New York: Simon and Schuster; 1982. p. 96.|
|7||Chethimattam JB. Consciousness and reality. London: Orbis Books; 1987. p. 85.|
|8||"Who". Maha Yoga. Sri Ramanasramam; 1984. p. 203-4.|
|9||Peat FD. Synchronicity: The bridge between matter and mind. New York: Bantam Books; 1987. p. 188.|
|10||Beck TE, Colli JE. Unity consciousness: A quantum biomechanical foundation. Subtle Energies and Energy Medicine, Vol. 14. 2003. p. 267-301.|