Out-of-Body Experiences: Theories and Evidence

Out-of-Body Experiences (OBEs) are phenomena in which individuals perceive themselves as detached from their physical bodies, often observing themselves from an external perspective. This article explores the various theories and empirical evidence surrounding OBEs, drawing from neurological, psychological, and transpersonal perspectives. Neurological models suggest that disruptions in brain regions such as the temporal-parietal junction play a key role in OBEs, while psychological theories link these experiences to dissociative states and altered consciousness. Transpersonal psychology views OBEs as transformative spiritual experiences, offering insights into higher states of consciousness. Empirical research, including phenomenological reports and laboratory studies, provides both supporting and critical evidence, while controversies continue regarding the verification of veridical OBEs. The article concludes by discussing the implications of OBEs for consciousness studies and suggesting directions for future research in transpersonal psychology.

Introduction

Out-of-Body Experiences (OBEs) refer to the phenomenon where individuals report the sensation of leaving their physical body, often observing themselves from a distance or in another location. These experiences are typically characterized by a sense of detachment from the physical self, spatial dislocation, and vivid perceptions, even in the absence of sensory input (Blackmore, 2017). OBEs have been reported throughout history, appearing in a variety of cultural and religious contexts, from shamanic practices to the astral projection traditions of Hinduism and Western esotericism. Despite their long history, OBEs continue to pose significant challenges for modern science, as they question the conventional understanding of consciousness as being entirely brain-based (Irwin & Watt, 2007).

Within transpersonal psychology, OBEs are seen as significant experiences that go beyond the ordinary limits of ego and physical identity. Transpersonal psychology, which explores the intersections of psychology and spirituality, views OBEs as gateways to higher states of consciousness and spiritual insight (Walsh & Vaughan, 1993). These experiences challenge the reductionist view of consciousness by suggesting that the self can exist independently of the physical body, at least in subjective experience. Furthermore, OBEs are frequently reported during near-death experiences (NDEs), making them particularly important in studies of altered states of consciousness and the potential for survival of consciousness after physical death (Greyson, 2000).

Scientific interest in OBEs has grown significantly in recent decades, particularly within the fields of neuroscience and cognitive psychology. Researchers have sought to understand the neurological and psychological mechanisms behind OBEs, investigating how certain brain regions, such as the temporal-parietal junction (TPJ), are involved in constructing the sense of self and body ownership (Blanke et al., 2004). At the same time, empirical studies continue to explore the phenomenology of OBEs, collecting detailed reports from individuals who claim to have experienced these events. The intersection of neuroscience, psychology, and transpersonal studies makes OBEs a compelling area of research, contributing to broader debates about the nature of consciousness and the mind-body relationship (Kwon et al., 2022).

Theories of Out-of-Body Experiences

Neurological and Biological Explanations

From a neurological perspective, Out-of-Body Experiences (OBEs) are often explained as disruptions in brain regions responsible for body awareness and spatial orientation. One of the primary areas implicated in OBEs is the temporal-parietal junction (TPJ), a region located at the intersection of the temporal and parietal lobes. The TPJ is involved in integrating sensory information from various sources to create a coherent sense of body ownership and self-location (Blanke et al., 2004). Studies have shown that stimulation or lesions in this area can lead to OBE-like sensations, where individuals feel as though they are floating above their bodies or observing themselves from a distance (Blanke, 2012). These findings suggest that OBEs may arise from disturbances in the brain’s ability to correctly process sensory input and construct a unified bodily self.

Another key factor in understanding the neurological basis of OBEs is the role of the vestibular system, which helps regulate balance and spatial orientation. Disruptions in the vestibular system, such as those caused by stress, sleep deprivation, or certain neurological conditions, have been linked to OBE experiences (Lopez & Blanke, 2011). For example, individuals with epilepsy, particularly those with temporal lobe epilepsy, frequently report experiencing OBEs either as part of their seizures or during the aura preceding a seizure (Devinsky et al., 2009). This further supports the idea that OBEs can result from neurological disturbances that affect the brain’s ability to integrate sensory information and maintain body awareness.

In addition to specific brain regions, OBEs have been associated with certain neurochemical states. Research has suggested that altered levels of neurotransmitters, such as serotonin and dopamine, may play a role in inducing OBEs (Vaitl et al., 2005). These neurotransmitters are crucial for regulating mood, perception, and consciousness, and their dysregulation is thought to contribute to a wide range of altered states of consciousness, including OBEs. This is particularly evident in cases of near-death experiences (NDEs), where extreme physiological stress, such as cardiac arrest, can lead to a temporary alteration in brain chemistry, potentially triggering an OBE (Greyson, 2000).

Despite the compelling neurological evidence, there are limitations to this approach. While neurological models can explain the mechanics of OBEs in terms of brain function and sensory integration, they struggle to account for the subjective and often deeply meaningful nature of these experiences. OBEs are frequently described as profoundly real and transformative, leading many individuals to believe they have encountered a spiritual dimension or higher reality (Metzinger, 2005). The reduction of OBEs to mere brain dysfunction may fail to capture the richness of the experience, and critics argue that more integrative models are needed to fully understand the phenomenon.

Psychological Models

Psychological theories of OBEs focus on cognitive and perceptual processes that may lead to the experience of self-detachment. Cognitive models suggest that OBEs result from a breakdown in the brain’s normal processing of sensory and body-related information. When the brain misinterprets sensory signals, it can create the illusion of being located outside the physical body (Blackmore, 2017). For example, during states of sleep paralysis or hypnagogic hallucinations—conditions where individuals are conscious but unable to move—people often report OBE-like sensations. These experiences, occurring during transitions between sleep and wakefulness, suggest that OBEs may be linked to altered states of consciousness where normal sensory processing is disrupted (Cheyne & Girard, 2009).

Perceptual disembodiment, another psychological explanation, suggests that OBEs may result from a failure to integrate multisensory information into a coherent body schema. Under normal conditions, the brain continuously receives input from the senses, allowing it to maintain an accurate representation of the body’s position in space. However, in certain conditions—such as extreme stress, sensory deprivation, or trauma—the brain may lose this ability, leading to a sense of disembodiment (Irwin, 2000). This model is supported by research showing that individuals who frequently experience OBEs tend to have higher levels of absorption, dissociation, and fantasy proneness (Murray, 2009).

Psychological models also explore the role of personality traits and emotional states in OBEs. Dissociation, a psychological state where an individual feels disconnected from their thoughts, feelings, or body, has been closely linked to OBEs (Irwin & Watt, 2007). Individuals who are more prone to dissociation—often as a result of trauma, stress, or anxiety—are more likely to report OBE experiences. This is consistent with studies showing that OBEs frequently occur during moments of extreme psychological or physiological stress, such as during life-threatening situations, suggesting that OBEs may function as a psychological coping mechanism (Gabbard & Twemlow, 1984).

While psychological theories provide important insights into the cognitive and emotional mechanisms underlying OBEs, they also face limitations. Like neurological models, psychological explanations often reduce OBEs to distortions or failures in normal brain function, without addressing the subjective depth or potential transpersonal significance of the experience. For many individuals, OBEs are not simply psychological anomalies but transformative events that challenge their understanding of reality and consciousness (Metzinger, 2005). This has led to calls for more integrative approaches that consider both the psychological and transpersonal dimensions of OBEs.

Transpersonal and Spiritual Perspectives

From a transpersonal perspective, OBEs are viewed not merely as neurological or psychological anomalies but as profound spiritual experiences that offer insights into the nature of consciousness. In many spiritual traditions, OBEs are seen as moments of transcendence, where the individual temporarily disconnects from the ego and experiences a higher dimension of reality (Walsh & Vaughan, 1993). Shamanic traditions, for instance, often involve journeying into other realms of existence through altered states of consciousness, with OBEs being one of the primary methods for accessing these spiritual dimensions (Harner, 1990). Similarly, practices such as astral projection in Western esotericism involve intentional OBEs aimed at exploring non-physical realms.

Transpersonal psychology, which integrates spiritual and psychological approaches to understanding human experience, views OBEs as important phenomena that challenge materialist conceptions of consciousness (Wilber, 2000). According to this perspective, OBEs may reflect the capacity of consciousness to transcend the physical body and access higher states of awareness. These experiences are often associated with feelings of unity, interconnectedness, and spiritual insight, suggesting that OBEs can be transformative events with long-term psychological and spiritual significance (Walsh & Vaughan, 1993). In this framework, OBEs are not simply disruptions in normal consciousness but opportunities for growth and exploration of the transpersonal dimensions of the self.

Ken Wilber’s Integral Theory provides a framework for understanding OBEs within the broader context of human development. Wilber (2006) posits that consciousness evolves through a series of developmental stages, moving from egocentric to ethnocentric, and ultimately to transpersonal stages. OBEs, according to Wilber, may occur at various stages of development but are particularly significant in the transpersonal stages, where individuals begin to transcend the limits of ego and experience non-ordinary states of consciousness. OBEs, in this view, are part of the broader spectrum of human potential and spiritual awakening, offering insights into the nature of reality beyond the physical self.

Despite their significance in transpersonal psychology, spiritual interpretations of OBEs remain controversial within mainstream science. Critics argue that spiritual explanations rely too heavily on subjective reports and lack empirical support, making them difficult to verify or test (Blackmore, 2017). Furthermore, the spiritual significance of OBEs is often dismissed as mere psychological or neurological phenomena. However, proponents of transpersonal psychology maintain that OBEs represent a unique and valuable window into the study of consciousness, one that cannot be fully explained by reductionist approaches (Walsh & Vaughan, 1993).

Empirical Evidence of Out-of-Body Experiences

Phenomenological and First-Person Accounts

Phenomenological research on Out-of-Body Experiences (OBEs) has relied heavily on first-person accounts to explore the subjective nature of these experiences. Individuals who report OBEs often describe sensations of floating, observing their physical bodies from an external vantage point, or traveling to distant locations (Metzinger, 2005). These accounts have been documented across different cultures and time periods, suggesting that OBEs may be a universal phenomenon. Common themes in these reports include vivid perceptions, a sense of detachment from the physical body, and heightened clarity or awareness. For example, Alvarado (1992) analyzed multiple first-person narratives of OBEs and found that individuals consistently report feeling as though their consciousness has left their physical body and exists in an alternate space.

Cultural variations in OBE accounts have been observed, although the core experiences remain similar. In Western cultures, OBEs are often associated with spiritualism and the concept of astral projection, while in Eastern traditions, they may be interpreted as part of meditation practices or shamanic journeys (Walsh & Vaughan, 1993). Despite these differences in interpretation, the essential characteristics of the experience—such as detachment from the physical body and perception of the self from an external viewpoint—are remarkably consistent across different cultural contexts. These findings support the notion that OBEs are not merely a cultural or psychological anomaly but may reflect a more universal aspect of human consciousness.

However, the reliance on subjective reports presents challenges for scientific validation. First-person accounts of OBEs, while rich in detail, are inherently difficult to verify. The subjective nature of OBEs raises concerns about the accuracy of these experiences, particularly when individuals claim to perceive real-world events or objects while out of their bodies. Critics argue that without objective measures, it is difficult to distinguish genuine OBEs from hallucinations or misperceptions (Blackmore, 2017). Nevertheless, the consistency of phenomenological reports across different cultures and historical periods provides valuable insights into the nature of OBEs, even if these accounts remain difficult to empirically validate.

Laboratory Studies and Induced OBEs

Laboratory studies have attempted to induce Out-of-Body Experiences (OBEs) in controlled settings, providing valuable insights into the neurophysiological mechanisms behind the phenomenon. One of the most notable experimental approaches involves the use of virtual reality (VR) technology to create OBE-like sensations. In these experiments, participants wear VR headsets that project a visual image of their body from a third-person perspective, creating the illusion of observing themselves from outside their physical form (Ehrsson, 2007). This technique has successfully induced OBE-like experiences in a significant number of participants, providing empirical support for the idea that OBEs can be triggered by manipulating sensory input and disrupting the brain’s body representation processes.

Another experimental approach involves the use of transcranial magnetic stimulation (TMS) to target specific areas of the brain involved in body perception, such as the temporal-parietal junction (TPJ). Blanke et al. (2004) demonstrated that stimulating the TPJ in patients with neurological disorders could induce sensations of detachment from the physical body, resembling an OBE. These findings suggest that OBEs may be the result of disruptions in the brain’s multisensory integration processes, where the TPJ plays a critical role in constructing the sense of bodily self-location. By manipulating these brain regions in controlled settings, researchers have been able to recreate key aspects of the OBE experience, providing a neurological basis for the phenomenon.

While these laboratory studies have been successful in inducing OBE-like experiences, they also face certain limitations. The OBEs generated in experimental settings are often less vivid and transformative than those reported in natural settings, such as during near-death experiences (NDEs) or spontaneous OBEs. Moreover, the artificial nature of induced OBEs raises questions about their authenticity and whether they can truly replicate the richness of real-world OBEs (Metzinger, 2005). Nonetheless, these experiments have contributed significantly to our understanding of the neurological underpinnings of OBEs, offering a controlled way to explore the phenomenon in a scientific context.

OBEs and Near-Death Experiences

Out-of-Body Experiences (OBEs) frequently occur as part of Near-Death Experiences (NDEs), making them a key area of investigation for researchers studying altered states of consciousness. NDEs often involve an individual undergoing a life-threatening event, such as cardiac arrest, and reporting vivid experiences that include leaving their physical body and observing events from a detached perspective (Greyson, 2000). Many NDE accounts include detailed descriptions of OBEs, where individuals claim to have seen their own bodies from above, witnessed medical personnel working on them, or traveled through otherworldly realms. These experiences often have a profound psychological and spiritual impact on the individuals who experience them, leading to lasting changes in their attitudes toward life and death (Holden, 2009).

Empirical studies on NDEs have provided intriguing evidence for OBEs, particularly in cases where individuals report veridical OBEs—experiences in which they accurately perceive events or objects from an external perspective that they could not have known from their physical vantage point. For example, some individuals have reported seeing specific details of their medical procedures or hospital environments while they were clinically unconscious or physically incapable of perceiving their surroundings (Parnia et al., 2014). These veridical OBEs challenge conventional explanations of OBEs as mere hallucinations or misperceptions, suggesting that there may be more to the phenomenon than can be explained by current scientific models.

Despite these compelling reports, veridical OBEs remain highly controversial. Skeptics argue that such accounts could be the result of post-hoc rationalization, selective memory, or subconscious awareness of environmental details rather than evidence of consciousness existing outside the body (Blackmore, 1996). Moreover, attempts to empirically verify veridical OBEs in controlled settings have yielded mixed results, with no conclusive evidence to support the existence of consciousness independent of the brain (Holden, 2009). Nevertheless, the relationship between OBEs and NDEs continues to be a rich area of inquiry, raising important questions about the nature of consciousness and its potential to transcend the physical body.

Controversies and Criticisms

Skeptical Interpretations of OBEs

Skeptical interpretations of Out-of-Body Experiences (OBEs) argue that these phenomena can be entirely explained by physiological and psychological mechanisms, dismissing any claims of transcendence or spiritual significance. From a materialist perspective, OBEs are often seen as cognitive distortions or sensory illusions that occur due to disruptions in normal brain functioning. Susan Blackmore (2017), a well-known skeptic, contends that OBEs can be fully understood in terms of how the brain processes sensory input and constructs the experience of the self. According to this view, OBEs are not evidence of a separate, non-physical aspect of consciousness but rather the result of a brain malfunction, often triggered by stress, fatigue, or neurological conditions. The frequent association of OBEs with sleep paralysis, near-death experiences (NDEs), and certain drugs lends support to the theory that these experiences are rooted in neurochemical imbalances or sensory misperceptions (Cheyne & Girard, 2009).

Critics also point out that many of the claims made by OBE experiencers, particularly regarding “veridical” perceptions, are difficult to verify empirically. Veridical OBEs—where individuals report perceiving real-world events from an out-of-body perspective—are often cited as evidence of consciousness existing independently of the brain. However, skeptics argue that such reports could result from a combination of prior knowledge, subconscious perception, and post-hoc rationalization (Blackmore, 1996). In controlled experiments designed to test veridical OBEs, results have been inconsistent, with most studies failing to provide definitive evidence that individuals can perceive events or objects during OBEs that they could not have known through normal sensory means (Hines, 2003). As a result, many researchers in the scientific community remain skeptical of the idea that OBEs represent anything beyond the brain’s capacity to generate altered states of consciousness.

Challenges in Verifying Subjective Experiences

One of the central challenges in studying Out-of-Body Experiences (OBEs) is the subjective nature of the phenomenon. OBEs, like many altered states of consciousness, are deeply personal and inherently difficult to quantify or verify objectively. First-person reports form the bulk of the data on OBEs, but these accounts are prone to biases, memory distortions, and inaccuracies. While phenomenological studies have provided valuable insights into the common characteristics of OBEs, such as the sensation of floating or observing one’s body from above, they do not offer a way to measure or objectively validate the experience (Metzinger, 2005). Critics argue that relying solely on subjective reports limits the scientific rigor of OBE research, as it becomes difficult to separate genuine experiences from hallucinations, dreams, or misinterpretations of sensory input.

Moreover, empirical studies designed to verify OBEs have faced significant methodological challenges. In laboratory settings, researchers have attempted to induce OBE-like experiences using techniques such as virtual reality (VR) and transcranial magnetic stimulation (TMS) to stimulate brain regions associated with body perception (Ehrsson, 2007). While these experiments have successfully replicated some of the sensations associated with OBEs, such as the feeling of detachment from the body, the artificially induced experiences are often less vivid and convincing than natural OBEs. This raises questions about the ecological validity of such studies and whether they can truly replicate the richness of a spontaneous OBE. Additionally, the difficulty in obtaining veridical evidence—cases where individuals accurately report perceiving details of their environment from an out-of-body perspective—has further hindered the empirical validation of OBEs (Holden, 2009). As a result, the study of OBEs remains a contentious field, with ongoing debates about how best to measure and verify such elusive experiences.

Ethical and Philosophical Considerations

The ethical implications of research on Out-of-Body Experiences (OBEs) are another area of controversy. Inducing OBEs in laboratory settings, particularly through the use of techniques like brain stimulation or virtual reality, raises concerns about the potential psychological effects on participants. OBEs are often described as deeply disorienting and, for some individuals, may trigger anxiety or confusion about their sense of self and reality (Metzinger, 2005). Researchers have a responsibility to ensure that participants are fully informed of the potential risks associated with OBE-inducing experiments, and ethical guidelines must be established to protect their well-being. Moreover, given that OBEs are often associated with traumatic events or near-death experiences, some critics question the ethics of deliberately inducing these states for experimental purposes (Greyson, 2000).

Philosophically, OBEs also challenge foundational ideas about the nature of consciousness and the mind-body relationship. From a dualist perspective, OBEs are often interpreted as evidence that consciousness can exist independently of the physical body, offering support for the notion of an immaterial soul or non-physical aspect of the self (Wilber, 2006). However, materialist philosophers and neuroscientists argue that OBEs can be fully explained by brain processes, with no need to invoke non-physical explanations. This debate touches on broader questions about the nature of consciousness, the possibility of life after death, and the limitations of scientific inquiry into subjective experiences (Chalmers, 1996). As research into OBEs continues, these ethical and philosophical considerations will remain central to the ongoing exploration of consciousness and its potential to transcend the physical body.

Conclusion

Out-of-Body Experiences (OBEs) remain a compelling and widely reported phenomenon that bridges the domains of neuroscience, psychology, and transpersonal studies. Theoretical explanations range from purely biological accounts that emphasize the role of specific brain regions, such as the temporal-parietal junction (Blanke et al., 2004), to psychological theories that suggest OBEs arise from cognitive distortions or dissociative states (Irwin & Watt, 2007). At the same time, transpersonal perspectives emphasize the spiritual and transformative dimensions of OBEs, interpreting them as experiences that challenge the materialist conception of consciousness (Walsh & Vaughan, 1993). While each of these frameworks offers valuable insights, the complexity of OBEs indicates that no single explanation can fully account for the phenomenon.

Empirical evidence supporting OBEs comes from a variety of sources, including first-person phenomenological accounts, laboratory-induced OBE experiments, and studies on OBEs within near-death experiences (Greyson, 2000). Although phenomenological research provides rich descriptions of the subjective experience, it struggles with verification, especially in claims of veridical perception. Laboratory studies, while successful in replicating some aspects of OBEs, often produce experiences that lack the depth and vividness of naturally occurring OBEs (Ehrsson, 2007). The link between OBEs and near-death experiences continues to be one of the most intriguing areas of research, particularly with reports of individuals accurately perceiving events during periods of clinical unconsciousness (Holden, 2009). However, these studies remain controversial, and more rigorous methodologies are required to validate such claims definitively.

The future of OBE research will likely involve a more integrative approach, combining insights from neuroscience, psychology, and transpersonal studies. As research techniques become more sophisticated, particularly in neuroimaging and brain stimulation technologies, there may be greater potential for understanding the neural correlates of OBEs. Simultaneously, qualitative research exploring the spiritual and psychological dimensions of OBEs is crucial for appreciating the subjective and transformative aspects of the experience (Metzinger, 2005). By continuing to explore OBEs through both empirical and phenomenological lenses, researchers may gain deeper insights into the nature of consciousness and the potential for human experience to transcend the physical body.

Bibliography

1. Alvarado, C. S. (1992). Out-of-body experiences: A psychological theory. Journal of the Society for Psychical Research, 58(826), 187-203.
2. Blackmore, S. (1996). Dying to live: Near-death experiences. Prometheus Books.
3. Blackmore, S. (2017). Seeing myself: The new science of out-of-body experiences. Robinson.
4. Blanke, O. (2012). Multisensory brain mechanisms of bodily self-consciousness. Nature Reviews Neuroscience, 13(8), 556-571. https://doi.org/10.1038/nrn3292
5. Chalmers, D. (1996). The conscious mind: In search of a fundamental theory. Oxford University Press.
6. Cheyne, J. A., & Girard, T. A. (2009). The body unbound: Vestibular–motor hallucinations and out-of-body experiences. Cortex, 45(2), 201-215. https://doi.org/10.1016/j.cortex.2007.05.002
7. Devinsky, O., Feldmann, E., Burrowes, K., & Bromfield, E. (2009). Autoscopic phenomena with seizures. Archives of Neurology, 46(10), 1080-1088. https://doi.org/10.1001/archneur.1989.00520460062023
8. Ehrsson, H. H. (2007). The experimental induction of out-of-body experiences. Science, 317(5841), 1048. https://doi.org/10.1126/science.1142175
9. Gabbard, G. O., & Twemlow, S. W. (1984). With the eyes of the mind: An empirical analysis of out-of-body states. Praeger.
10. Greyson, B. (2000). Near-death experiences. In L. E. Sullivan (Ed.), Death, afterlife, and the soul (pp. 456-459). Macmillan.
11. Harner, M. (1990). The way of the shaman. Harper & Row.
12. Hines, T. (2003). Pseudoscience and the paranormal. Prometheus Books.
13. Holden, J. M. (2009). Veridical perception in near-death experiences. In J. M. Holden, B. Greyson, & D. James (Eds.), The handbook of near-death experiences: Thirty years of investigation (pp. 185-211). Praeger.
14. Irwin, H. J. (2000). The disembodied self: An empirical study of dissociation and the out-of-body experience. Journal of Parapsychology, 64(3), 261-277.
15. Irwin, H. J., & Watt, C. A. (2007). An introduction to parapsychology (5th ed.). McFarland.
16. Kwon, H., Ortiz, T., & Blanke, O. (2022). Brain mechanisms of out-of-body experiences. Nature Reviews Neuroscience, 23(4), 270-281. https://doi.org/10.1038/s41583-021-00571-0
17. Lopez, C., & Blanke, O. (2011). The vestibular cortex in the brain: Multisensory integration for body perception. Annals of the New York Academy of Sciences, 1236(1), 279-298. https://doi.org/10.1111/j.1749-6632.2011.06245.x
18. Metzinger, T. (2005). Out-of-body experiences as the origin of the concept of a “soul”. In T. Metzinger (Ed.), The ego tunnel: The science of the mind and the myth of the self. Basic Books.
19. Murray, C. D. (2009). Psychological correlates of the out-of-body experience. Journal of Mental Health, Religion & Culture, 12(5), 441-448. https://doi.org/10.1080/13674670802267385
20. Parnia, S., Spearpoint, K., & Fenwick, P. (2014). Near death experiences, cognitive function and psychological outcomes of surviving cardiac arrest. Resuscitation, 85(12), 1799-1805. https://doi.org/10.1016/j.resuscitation.2014.09.011
21. Vaitl, D., Birbaumer, N., Gruzelier, J., et al. (2005). Psychobiology of altered states of consciousness. Psychological Bulletin, 131(1), 98-127. https://doi.org/10.1037/0033-2909.131.1.98
22. Walsh, R., & Vaughan, F. (Eds.). (1993). Paths beyond ego: The transpersonal vision. Tarcher.
23. Wilber, K. (2000). A brief history of everything. Shambhala.
24. Wilber, K. (2006). Integral spirituality: A startling new role for religion in the modern and postmodern world. Shambhala.