Allowing Similarities: Using Aldous Huxley’s Views on Mystical Experience to Assess the Import of Profound Unitive Experiences Occasioned by Psychedelic Substances

Abstract

For more than four decades, the emphasis in the academic study of world religions has been on differences over similarities, and comparative analyses allowing for commonalities have become increasingly rare. This article argues that similarities nonetheless exist and should be studied. After disclaiming the judgment of other scholars that Aldous Huxley attempted to describe the “core” or “essence” of mystical experience, the article continues with a description of Huxley’s unitive mystical experience as simply a thread running across the traditions, evidenced by the fact that it is often found in both the primary and secondary literature of mysticism. The essay then goes on to cite descriptions of unitive experiences in research studies with psychedelics. Given that these experiences regularly occur with psilocybin and other drugs, as studies show, the article argues that the use of psychedelics is currently providing a rich source of experiential reports from which scholars of mysticism may glean insights. Furthermore, based on the views of Huxley, and supported by the reports of Roland Griffiths, Jussi Jylkka, David Yaden, William Richards, Julie Holland and others, the article speculates about the possible benefits of unitive mystical experiences triggered by psychedelics for both the individual and society.

“Like sensitivity to beauty, the capacity to encounter the Holy seems to reside within every human soul. Too often it may sleep there eternally, but it is ready to be awakened by the right combination of circumstances.”

Walter Houston Clark (Clark 1969, p. 89)

“I feel, and I think that Sid [psychiatrist Sidney Cohen] does too, that the best possible therapeutic LSD experience is one in which a subject glimpses the unity of the cosmos and his own place in it.”

Betty Grover Eisner, 1957 (quoted in Gelberg 2025, p. 32)

1. Introduction

The primary goal of this essay is to argue that similarities of mystical experience indeed exist across numerous traditions; that Aldous Huxley’s unitive mystical experience is one such thread of similarity; that these unitive experiences also often occur under the influence of psychedelic substances, as evidenced by studies today; and that there is preliminary support for the position that these experiences have great value for the individual, society, and the environment. Because the essay relies on Huxley’s viewpoint, it does not claim the unitive mystical experience is a form of “pure” or unmediated consciousness, nor does it claim such experiences are the “core” or “essence” of religion or mysticism—a position Huxley did not hold. Furthermore, though the essay agrees with Huxley that the unitive mystical experience is likely to occur universally (as, for instance, do aesthetic experiences and experiences of love), it also agrees with him that the experience is mediated by cultural influences, weighed differently in different cultures (sometimes even discarded altogether), with no proposition here of a universalist religion or ideology. The hope implicit in this essay is that scholars of religious studies will re-embrace the reality of similarities of experience across the mystical traditions, allowing the serious study of their import, while also allowing that the existence of differences—and mediated elements of unitive experience—do not necessarily exclude the possibility that elements of similarity may also exist.

For more than forty years now, the emphasis in the academic study of world religions has been on differences over similarities, and comparative analyses allowing for commonalities have become increasingly rare. The reasons for this trend, beginning in the late 1970s, are various, including post-colonial concerns that the search for cross-cultural similarities has been—and implicitly becomes—a renewed form of colonialism, imposing a universalist umbrella over the world’s religions that privileges Western judgments on them (first argued by J. Z. Smith 1982)1 Such concern over the study of similarities, especially in the service of any form of overarching “meta-narrative,” has also been shared by postmodernists, who worry that such narratives disrespect cultural differences and generate new power structures that marginalize those who disagree with them (first argued by Jean-Francois Lyotard [1979] 1984). In the study of mystical experiences, this trend found its champions with the constructivists/contextualists, who argued that all experiences—including mystical experiences—are shaped and “mediated” by cultural conditioning such that each tradition is siloed within itself. Consequently, the constructivists argued, Christians have Christian mystical experiences, Hindus have Hindu mystical experiences, Muslims have Islamic mystical experiences, etc., with contextualized boundaries between them, disallowing any chance of commonalities (first argued by Steven T. Katz 1978).2 Whether these scholars are right or wrong—or to what extent they are either right or wrong—is not the point here, but rather I am simply citing some of the generally accepted reasons for why attention shifted away from similarities.

2. But What About the Definite Similarities? Can They Be Allowed?

And yet, the unspoken problem that has remained with us—not just for the past few decades but over the past four millennia—is that all ideologies, whether religious or philosophical, have been generated by exactly one species. Consequently, isomorphism alone would account for inevitable similarities of experience if not of interpretation, in that our senses and brains gain traction on the world in exactly the same way, and with exactly the same limitations. As the anthropologist Nicolas Langlitz has put it, having recognized definite similarities: “Maybe the spiritual experiences of human beings do not resemble each other across cultures because they point to the same God or universal truth but simply because human brains all work alike” (Langlitz 2013, p. 228). This is not to say that differences do not matter; it is to argue that differences are not all that matters. In religious studies today, this is a hard point to make for reasons just mentioned—and as others have also mentioned.3

Moving forward, our brains and senses have—over the eons—produced discernible cross-cultural phenomena, including not only such early rudiments as language and tool making, but an undeniable attraction to story-telling, music, artwork, and the search for meaning. Cultures differ in how they express these phenomena, but all cultures express them, and given that they do, we can expect—without much effort actually—some commonalities and patterns of similarity, despite the many differences. For instance, without denying that musical forms in myriad cultures have myriad differences, and without trying to claim a universalist form of music, we are not being overly bold to say that rhythm is a commonly occurring, cross-cultural element of music. Cultural similarities, I argue, are simply real phenomena that deserve to be accepted, and it is possible to analyze them from the perspective of religious studies and comparative mysticism without projecting a priori assumptions, without suggesting an unnecessary hybrid religion or reductive universalism, and without disrespecting differences.4

All of the above is pertinent to this essay in that Aldous Huxley’s perennial philosophy has generally been dismissed out of hand over the past forty years on charges of being essentialist, universalist, reductionist, unmindful of socio-linguistic programming, or disrespectful of cultural diversity. Specifically, there have been repeated attacks against Huxley’s position on the grounds that he and other perennialists have claimed to identify the “core” or “essence” of all religion (e.g., Bowker 2000, p. 446) and/or of all mysticism (e.g., R. H. Jones 2022, pp. 659–78), whereas neither charge, in either regard, is actually true—as I’ve argued in detail elsewhere (Sawyer 2021). It is interesting to note that many if not most accusations against perennialists have included no actual citations from their work. For instance, in Katz’s highly influential criticism of Huxley and the perennial philosophy from 1978, he quoted exactly nobody, suggesting that he had characterized the position accurately without giving support (Katz 1978, pp. 23–24). Meanwhile, Huxley’s specific viewpoint, first stated in his 1945 book The Perennial Philosophy, escapes Katz’s critique entirely. In fact, with reference to the notion that Huxley was trying to identify the core of religion, Huxley’s book, which was the first iteration of the perennial philosophy in modern times, does not even include an entry for “religion” in its index. Furthermore, as I have also argued, the perennial philosophy has generally been misunderstood over the past four decades as a siloed or monolithic position, whereas it is actually a family of interrelated theories (analogous to such other schools of thought as existentialism, postmodernism, and phenomenology), with the majority opinion—including Huxley’s—against the idea of a ‘mystical core of religion.’ In fact, the majority of self-identifying perennialists today are drawn from the field of psychology, with little to no interest in religion at all.

Dealing with Huxley specifically, what was his position on mystical experience, and why might we reconsider it today, during this time of the so-called Psychedelic Renaissance? Huxley argued that when he looked across the literature of the world’s mystical traditions, as well as at the secondary literature of his own time (more on this point presently), he could identify several common threads of experience, including descriptions of psi phenomena, experiences of profound unity, entity encounters, and “visionary experiences,”5 but of all these threads he privileged the “unitive knowledge” (Huxley [1945] 2004, p. 21) as likely to have the most value. Briefly, the unitive knowledge for Huxley is the direct experience that registers on the subject as having achieved oneness with Ultimate Reality, the Ground of Being, God, the Sacred, etc.—a union with an ontological Absolute, however variously conceived or described. Huxley did not say this experience is the core of religion or mysticism; he did say that of the many threads of experience he could see running across the traditions, the “unitive knowledge” struck him as the “highest common factor” (ibid., p. vii), based not only on its prevalence in the literature but the value that mystics themselves generally placed upon it. With regard to religion, Huxley’s indifference to the subject suggests he was perfectly willing to let the traditions decide for themselves what their mystical core was. In summary, Huxley was interested in a particular type of cross-cultural mystical experience he deemed valuable, but was not an essentialist regarding mystical experience.

As I have already related, Huxley termed the experience of profound mystical union the “unitive knowledge,” because he believed it has implicit, self-validating epistemic value, conveying experiential insight into the fundamental relationship between ourselves and the cosmos. Setting that epistemic claim aside for now, I will refer to this profound mystical union henceforth as the unitive mystical experience, given that I see it not only as Huxley’s central concern but as the shared focus of the majority of perennialist positions today (e.g., see Sawyer 2024).6 In short, the experience itself is the dominant focus of perennialists, not what it points to ontologically or how it may or may not relate to religion, but we will return to the issue of epistemology later.

That the unitive mystical experience (UME) can be identified in the cross-cultural literature of mysticism (the same literature that constructivists have relied upon) is defensible, as Huxley indeed argued. One need not labor long and hard to find examples; they abound. For instance, the Catholic mystic Jan van Ruysbroeck (1293–1381) wrote: “For to comprehend and understand God above all similitudes, such as he is in Himself, is to be God with God” (Happold [1963] 1970, p. 100). Ibn Arabi (1165–1240), the Muslim mystic, also described his union as a sort of complete absorption: “Then…the even and the odd come together, He is and you are not…. He sees Himself through Himself [i.e., through you]” (Shah-Kazemi 2006, p. 101). Isaac of Acre, the Thirteenth Century Kabbalist, described his complete absorption into God using the image of a jug of water being submerged in a “running well.” The water of the jug merging fully with that of the well and losing all separation (Paper 2004, pp. 24–25). And to give but one more example: the Mahavakyas of Hinduism’s Advaita Vedanta tradition, include the pronouncement Aham Brahmasmi or “I am Brahman,” claiming the unity of the individual self with Ultimate Reality.

Such experiences can be—and have been—variously described and interpreted, since the experiences are no doubt mediated by the cultural backgrounds of the various mystics, as Huxley himself had argued,7 but the prevalence of unitive experiences in the traditional reports, including the similarities in their descriptions, is difficult to reason away. The fact is that the UME and the advice to seek it are so persistent in the literature that the majority of scholars who have focused on mystical experience for more than a century have positioned profound unitive experiences as a principal matter—whether a “core” or not. Let us take a look.

William James was one of the first to emphasize the importance of the UME, writing in The Varieties of Religious Experience (1902): “This overcoming of all the usual barriers between the individual and the Absolute is the great mystic achievement. In mystic states we both become one with the Absolute and we become aware of our oneness” (James [1902] 1929, p. 410). However, we also find the UME as the principal mystical experience described in the work of (in chronological order) William Ralph Inge ([1899] 1956),8 R. M. Bucke (1901), Friedrich von Hugel (1908), Evelyn Underhill (1915),9 R. M. Jones (1924),10 Rudolf Otto ([1926] 1932),11 Robert Charles Zaehner (1957),12 Walter Terence Stace (1960), Frederick Crossfield Happold ([1963] 1970), Ninian Smart (1965),13 Hal Bridges (1970),14 Steven Payne (1998),15 Nelson Pike (1994), Peter Moore (2005),16 Richard King (2005),17 Suzanna Szugyiczki (2023), Saeed Zarrabizadeh (2008), and others. Admittedly, some of this trend toward the UME as a primary and often central focus in the academic study of mystical experience results from later scholars relying on the conclusions of earlier ones, as was definitely the case with Happold, who relied overly on the views of Underhill, but in most instances this charge simply does not hold. The majority of the scholars just mentioned reached their own conclusions based on their own analyses.

Furthermore, arguments against studying cross-cultural similarities of mystical experience—including the UME—have relied mainly on the work of Steven Katz, Robert Gimello, and Wayne Proudfoot, and yet the viewpoint of these “hard constructivists” has undergone severe criticism of its own. Regarding Katz’s 1978 article specifically, Bruce Janz has observed: “If the measure of the success of a philosophical article is how much attention it commands, Katz’s article is a winner. Relatively little of the attention has been positive, however” (Janz 1995, p. 78). To which Janz adds a laundry list of critics of the constructivist position, including: Gary Kessler, Norman Prigge (Prigge and Kessler 1990), Peter Byrne, James Robertson Price, J.W. Forgie, Huston Smith, Donald Evans, Sallie B. King, Robert Forman, Jonathan Shear, Michael Stoeber, and Nelson Pike—to which I would add Jonathan Herman (2000, pp. 92–100), Reza Shah-Kazemi (2006, pp. 229–40), and Paul Marshall (2005, pp. 180–90).

The primary distillation of the criticisms above18 for the present essay is that there is no settled opinion preventing the recognition of similarities across cultures, including within the discipline of comparative mysticism. The individual traditions certainly have differences, but they are not each siloed or sui generis, i.e., so unique and alien from each other that similarities can not be identified. We need not swing the pendulum back to the “deep structures” of Claude Levi-Strauss or the “transhistorical structures” of Mircea Eliade, and certainly not to the Euro-centric judgements of Sir James Frazer or Edward Burnett Tylor, but there is definitely room to explore similarities—including Huxley’s positing of a cross-cultural UME. In fact, the reliable occurrence of the UME in the primary literature is exactly why the UME has been cited as the principal element in the secondary literature. In summary, theories based on similarities are only reductionistic if their theorists claim no other approach to the study of mysticism is possible and no other mystical experiences have value; conversely, if we use the same metric, constructivists and postmodernists have been reductionistic, arguing that only differences matter.

Returning to Huxley’s viewpoint, the cross-cultural similarities of the UME suggested to him that they might derive from something endemic to the human psyche, as for instance is the arising of a sense of personal self or ego (however culturally mediated), though for a majority of us the direct experience of union with ultimate reality may only be a latent potentiality, rarely experienced. Mystics may have had—and may still have—an exceptional talent for such experiences, perhaps of the sort Ramon Panikkar termed the capax dei or “capacity for God” (Panikkar 2006, p. 30). But Huxley believed this latent potentiality could be developed—for instance by using the very methods of prayer, contemplation, yoga, meditation, etc., used by mystics. However, in 1945, he could see no reliable method by which the everyday person, unwilling to commit to these traditional practices, could access this latent ability—though his opinion soon changed.

3. Psychedelic Drugs as a Reliable Trigger of UMEs

A sea-change in Huxley’s viewpoint arose on 4 May 1953, when he first tried a psychedelic. Mescaline was not illegal at the time, and Humphry Osmond, a British psychiatrist working in Canada, indulged Huxley’s wish to try it. The experience was revelatory for Huxley, convincing him that brain-chemical change via a psychedelic drug could affect the same changes triggered by traditional methods, resulting—at least sometimes—in the same experiences had by mystics (Huxley [1954] 1970, p. 18). Though Zaehner and others doubted that a drug could affect such changes, especially as the subjective approximates of what the mystics had experienced, Huxley arrived at the same conclusion later termed by W.T. Stace the principle of “causal indifference” (Stace 1960, pp. 29–31). Stace insisted that the validity of a mystical experience should be judged on its own terms—by the quality of the experience—rather than the events or circumstances that brought it about.

Huxley’s view that psychedelics can—but won’t necessarily—trigger UMEs indistinguishable from those described in the traditional literature was embraced by a great many psychologists, psychiatrists, philosophers, and scholars of religious studies in his own time, including Huston Smith, Abraham Maslow, Stanislav Grof, Frances Vaughan, Walter Houston Clark, Lisa Bieberman, Roger Walsh, James Fadiman, Timothy Leary, Anthony Suttich, etc. In fact so much so that Huxley, with the close assistance of Osmond, shifted the characterization of psychedelic experiences away from the view that they were uniformly “psychoto-mimetic,” (mimicked psychosis) toward the view that they were sometimes “mystico-mimetic,” mimicking mystical experience. And with this broadening of what the substances could occasion came a shift in the primary term used to describe mescaline, psilocybin, DMT, and LSD, replacing “hallucinogens” with “psychedelics,” the term suggested by Huxley and Osmond.

Setting aside the history of the embrace of Huxley’s viewpoint on psychedelics, we can ask: does this position hold true today? Now, when there are more studies involving psychedelics than ever before, is there evidence that people are having experiences of the unitive mystical sort? I think it is bountifully clear that they are, at least if we can trust the published reports from the field of psychedelic studies. Without referencing the preponderant attention to issues related to the Stace-Pahnke typology, the Hood Scale, or the Mystical Experience Questionnaire19—which includes an item for “unity”—if we simply look at the session reports of test subjects in the formal studies, along with the reports of the researchers themselves, we find ample testimony that UMEs occur—and that they are commonly interpreted to have involved union with something ultimate or absolute. Here are some representative examples:

• Roland Griffiths is well known for replicating the “Good Friday Experiment,” linking psychedelic experience to mystical experience, a study in which nearly 70% of test subjects reported their inner journey on psilocybin as one of the top five most meaningful experiences of their lives (Griffiths et al. 2006). Moreover, the experience of unity became so common in session reports that after nearly twenty years of studies with psilocybin, Griffiths observed that a sense of “unity/connectedness” is—along with a sense of preciousness and realness—one of the most commonly reported psychedelic experiences.20
• William Richards, a member of Griffith’s team at Johns Hopkins, relates in his book Sacred Knowledge: Psychedelics and Religious Experience (2016) that “unitive consciousness” is common during clinical sessions with psilocybin. In fact, it occurs so often that he devoted an entire chapter to the subject, arguing specifically that reliably occurring UMEs offer support for Huxley’s position (Richards 2016, p. 11).
• In 2016, Matthew M. Nour (Nour et al. 2016), Lisa Evans, David Nutt, and Robin Carhart-Harris wrote in Frontiers of Human Neuroscience that ego-dissolution correlates strongly with “unitive (mystical) experiences,” and that “experiences of ego-dissolution, unity, and dissolved ego-boundaries may be conceptually inseparable, occurring together during ‘peak’ psychedelic experiences.”
• Julie Holland, a psychiatrist, tells us in Good Chemistry: the Science of Connection from Soul to Psychedelics (2020): “One of the hallmarks of the psychedelic experience is a transcendent sense of unity” (Holland 2020, pp. xxi–xxii). And she adds: “So often the psychedelic experience peaks with a sense of connection with everything, that everything is connected,” an experience she calls the “peak oneness experience” (ibid., p. 233).
• In 2022, David Yaden and Andrew Newberg reported in their book The Varieties of Spiritual Experience not only that unitive experiences regularly occur but that, “Some psychedelic studies have found that it is the first ‘mystical’ factor, which includes items related specifically to feelings of unity, that is most predictive of later positive outcomes like well-being” (Yaden and Newberg 2022, p. 230).
• In 2023, Jussi Jylkka, a cognitive psychologist and philosopher researching psychedelics in Finland, wrote that a key aspect of psychedelic experience is the “sense of unity or ego dissolution, where the experienced boundary between subject and object vanishes.” He called this an experience of “unitary knowledge” because the experience seems to have epistemic value, a point, as we have seen, Huxley also made (Jylkka 2023, p. 153).
• In 2024, Christof Koch (2024), a specialist in cognitive and behavioral biology, related his experience of deep unity while under the influence of Ayahuasca in his book And Then I Am Myself the World. Specifically, he described a loss of individuated self, a feeling of no longer being just Christof, but rather a state of pure consciousness, in which he experienced a sense of unity with the universe, a feeling of being one with everything.

Other examples are easily found, but these should serve to make clear that UMEs can be triggered by psychedelics, lending support to the position that Huxley and Stace were correct on the issue of “causal indifference.” The state of consciousness is what matters, not what caused it. Furthermore, these studies also give support to Huxley’s theory that the ability to have UMEs may be latent in all people, and not just an anomalous aptitude of mystics. This reliability bodes well for the study of mystical experiences, including UMEs, given that the regular and multitudinous occurrence of such experiences will provide ample data for analysis. Fifty years ago, Fritz Staal wrote in Exploring Mysticism, his interesting critique of methods for studying mystical experience, that focusing on the experiences themselves seemed most efficacious, but added that, “a common drawback is lack of experience” (Staal 1975, p. xv). Staal noted that psychedelics might have helped this situation (ibid., e.g., see pp. 155, 167), but the substances were illegal at that time—even for scientific research.

If we, as an academic community, can allow the study of similarities, including the reality of the cross-cultural phenomenon of UMEs, then a new era of productive research can begin—perhaps even with practical benefits for therapy and self-actualization. Since psychedelics often trigger UMEs, we already have data related to positive behavioral changes resulting from them, and certainly more studies in this regard will be forthcoming—as will be necessary to determine real value. As Huston Smith wrote in the Journal of Philosophy over sixty years ago even if it becomes clear that psychedelics can generate “religious experiences,” it remains to be seen if they can generate “religious lives” (H. Smith 2000, p. 30). This summation remains true, but today the ban on research with psychedelics has been lifted, so we now have a new opportunity to explore the possibilities.

4. What Is the Potential Value of Having Unitive Mystical Experiences?

Returning to Huxley, what did he see as the under-appreciated potential of the “unitive knowledge?” What was his vision of its value(s)—and to what extent does his vision hold true today?

We have focused thus far on only one of the many discernible types of experience that have been labeled “mystical,” including experiences of entity encounters, divine presence, precognition, inner luminosity, etc. That is, we have separated out the UME from the others, not because it is the core of mystical experience but because it is one of the most discernible experiences as well as the one Huxley believed has the most value (Huxley 1955, p. 48). We have defined the UME as it occurs cross-culturally as a direct experience that registers on the subject as union with an ultimate principle—described variously as Ultimate Reality, the Ground of Being, God, the Absolute, etc. Such a mystical experience, as Szugyiczki notes, “fundamentally restructures one’s personal narratives and actions” (Szugyiczki 2023, p. 29), and preliminary research at the University of Northern Colorado by psychologist Susan F. Schneeberger supports the benefit of this restructuring—caused specifically by the “unitive/mystical experience” (Schneeberger 2010). In Huxley’s view, the primary benefit is a reorientation of the individual’s sense of self from that of an isolated psyche to that of a psyche that is synonymous with Mind-at-Large, i.e., consciousness at a cosmic scale contextualizing itself inside a particular head.

For Huxley, the benefits of this revision of self depend upon the mystics having been right that there is an ultimate ‘Something’ pervading the world of time and space that also transcends it, a Ground of Being that rises and takes shape as the world itself. The sense of deep identity with an absolute brought a sense of liberation. After a profound UME (Huxley termed it the unitive knowledge because he believed the experience has epistemic value, conveying a self-validating insight into our place in the world), things are different. As an individual, the person continues to accept that they are only a small speck in a complex and colossal cosmos, but on another level they have experienced themselves—or in Taves’s language, have given “attribution” to the sense of having done so—as non-different from the source of the cosmos. Using an analogy for this reorientation, often attributed to Rumi, “You are not a drop in the ocean, you are the entire ocean in a drop.”21 Consequently, according to the testimony, not only of many mystics but of subjects in psychedelic studies suffering from terminal illness, the existential fear of death is set inside the view that on some level of their being they are not subject to death and everything is somehow or other—as Huxley once put it—“All Right, Capital A, Capital R” (Huxley quoted in Bedford 1974, p. 720).

As evidence for this claim with regard to psychedelics, in December 2016, a study conducted at Johns Hopkins and New York University, published in the Journal of Psychopharmacology, reported that “some 80% of cancer patients showed clinically significant reductions in standard measures of anxiety and depression” after treatment with psilocybin (Ross et al. 2016). Furthermore, “In both trials, the intensity of the mystical experience volunteers reported closely correlated with the degree to which their symptoms subsided.” Michael Pollan, reporting on this study, observed: “The majority of volunteers who had a mystical experience reported that their fear of death had either greatly diminished or completely disappeared” (Pollan 2018, p. 79), adding, “So it may be that the loss of self leads to a gain in meaning” (ibid., p. 353). Huxley would characterize the change in terms of the previously described reorientation. By now it is well established, as Roseman et al. have noted, that “the occurrence of a profound, potentially transformative psychological experience [on psychedelics] is critical to the treatment efficacy” (Roseman et al. 2018, p. 2). And in this regard, but with direct reference to the efficacy of having had a UME, A. O. Ermakova has observed: “The feeling of being completely merged with the source of the universe can permanently change one’s theology and understanding of the cosmos” (Ermakova et al. 2022).

Beyond the individual, Huxley also argued that the reorientation triggered by UMEs benefits society, given that the behavior of the person who has had a UME often becomes more compassionate and altruistic. Having had an experience that registers as oneness with an ultimate principle, they—at least sometimes—have a sense that the Sacred is looking out at the world through their eyes. This, arguably, is what St. Catherine of Genoa meant when she wrote: “My ‘Me’ is God, nor do I recognize any other Me except my God Himself” (Huxley [1945] 2004, p. 11). She was not claiming she, Catherine, was God, nor was she claiming only that she was in agreement with God on all things; she was stating that her soul was one with that of God and He was looking out through her eyes. This expanded consciousness and sense of self explained for Huxley the tendency of mystics to exhibit compassion—not only toward other humans but, as in the case of St. Francis of Assisi, other species and the planet itself. The mystics now identify with the entire cosmos, not just their individual space within it—or as the contemporary self-described mystic Mirabai Starr has put it, when you “turn your gaze toward the holy mystery you once called God [and may still], the mystery follows you back out into the world.”22 And so the suffering of others becomes the suffering also of the reoriented ‘self,’ which is why Huxley believed that kindness is applied mysticism. Quoting Huxley, who quoted Meister Eckhart: “What a man takes in by contemplation [which Huxley elsewhere defines as unitive knowledge]…that he pours out in love” (Huxley [1945] 2004, p. 301).

But is there any evidence that UMEs occasioned by psychedelics result in positive changes in behavior toward others? Referencing earlier studies with psychedelics, Walter Houston Clark wrote in Chemical Ecstasy: Psychedelic Drugs and Religion (1969): “empathy often does result from psychedelic experience,” to which he added: “It grows naturally out of the experience of unity. If one identifies himself with all things, it follows that he feels at one with his fellow creatures and so acknowledges responsibility toward them” (Clark 1969, p. 84).23 Coming up to the present, we find the same observation in Holland’s Good Chemistry: the Science of Connection from Soul to Psychedelics (2020), where she compares the reorientation of ‘psychonauts’ toward the world (including a move toward altruism) to that of astronauts returning from space. Astronauts “often speak of the feeling they get when they spot the home planet for the first time out the windows of their rockets. […] This overwhelming sensation of our interconnectedness is so remarkable and identifiable that it has its own name: the Overview Effect” (Holland 2020, pp. 200–1).

The Overview Effect was first described by Edgar Mitchell, the sixth man to walk on the moon, who felt “an overwhelming sense of oneness, of connectedness. It wasn’t ‘Them and Us,’ it was ‘That’s me! That’s all of it, it’s one thing’” (Pollan 2018, pp. 358–59). And for many other astronauts as well, this experience generates a new perspective, quoting Holland again: “the Overview Effect seems to create a profound and lasting cognitive shift through many of the same psychological mechanisms as the ‘mystic-type experiences’ [had by those on psychedelics]—awe, vastness, interconnectedness, a sense of belonging to a collective far greater than the self” (Holland 2020, pp. 226–27). Holland adds that this Overview “inspires a protective, caregiving impulse.”

Other evidence of altruistic behavior resulting from meaningful psychedelic experiences is readily available (e.g., Olteanu and Moreton 2025, pp. 1–9), and it is my belief that further studies with psychedelics will not only add significantly to our understanding of many sorts of mystical experiences, but help substantiate Huxley’s claim that having them not only has therapeutic benefits for the individual but tremendous value for social and environmental change. He did not see psychedelic experiences, including even those of the UME sort, as a panacea, but he believed that they could deliver useful insights that spur change. I’ll give Huxley the last word here: “I am not so foolish as to equate what happens under the influence of mescaline or of any other drug, prepared or in the future preparable, with the realization of the end and ultimate purpose of human life…. All I am suggesting is that the mescaline experience is what Catholic theologians call ‘a gratuitous grace,’ not necessary to salvation but potentially helpful and to be accepted thankfully, if made available” (Huxley [1954] 1970, p. 73).

5. Addendum: Does It Matter What Is Experienced, Ontologically Speaking, During a UME?

What is the ‘Something’ experienced during a UME and does it matter whether or not it is ontologically real? Szugyiczki, discussing William James’s view on the matter, has written: “According to James, even if [the mystics’] object cannot be proven empirically, they might be deemed valid on a different basis: on their positive, constructive effects, as they enrich people’s lives morally and aesthetically” (Szugyiczki 2023, p. 35). I deeply agree with this pragmatism, as I believe Huxley would, but wonder: would the sense of meaning, identity, and purpose, i.e., compassion, resulting from a UME be as strong without the sense of having experienced something ontologically real? I do not think so.

In 1952, theologian Paul Tillich (1962) argued in The Courage to Be that it was a deep sense of personal meaning that gives people such courage, and without that meaning they are in danger of stalling out along life’s highway, sinking into ennui and purposelessness. With regard to UMEs, these experiences commonly convey a self-validating sense of meaning, but, speaking in terms of ideas, what do they actually mean? In other words, how should they be interpreted? Certainly, a wide range of interpretations is available from both inside the traditional religious literature, where, for example, the UME is at the center of concern in Hinduism and Sufism, and inside the world of psychedelics, where interpretations range from the religious (e.g., Santo Daime) to the highly philosophical (e.g., Bernardo Kastrup) to the borderlands of woo woo. Furthermore, as I’ve explained elsewhere (Sawyer 2024), all perennial philosophers privilege the unitive mystical experience, but psychological perennialists—including Robert Forman and William Parsons—argue that the UME has psychological value even if the person experiencing it is wrong that they united with—or were absorbed into—something beyond themselves. So perhaps it is best not to interpret the experiences at all? This seems to be proving difficult at a time when so many people are reliably having UMEs on psychedelics—including the feeling of having experienced something ontologically real—and seeking to make sense of them.

Peter Sjostedt-Hughes has argued that interpretation may actually extend the benefits of psychedelic experience, therapeutically and spiritually. He argues that, “A full personal integration of such unitive states requires philosophy in addition to the intense experience because, to borrow and buckle an old phrase, the rational system without the intuition is empty; the intuition without the rational system is blind” (Sjostedt-Hughes 2023, p. 213). Furthermore, he has observed in a recent TEDx Talk that, “Certain metaphysical experiences [on psychedelics] could then be viewed within a legitimate, rational-based, metaphysical perspective—and thus not quickly be dismissed as anomalous.”24 I agree with him entirely. I think that too often people return from a UME and have no words to express what they have experienced, causing them, at least in some cases, to relegate their experience to the file of ‘strange and anomalous,’ without further reflection. Moreover, they may be encouraged to do so—especially if the experience was occasioned by a ‘drug’—by friends and family who have never had such an experience. Acquaintances may argue that the experience was “all in your head” or otherwise a bit of sophistry better to ignore. But as Ann Taves has argued, “We need to be more sensitive to experiences that are genuinely creative and generate new insights and, in some cases, entirely new meaning systems” (Taves 2009, p. 99).

In the attributional approach that I’ve already mentioned, researchers can take a neutral stance on the ontological viability of what their subjects claim to have experienced, for instance relating that the person described an experience that “seemed like” union with ultimate reality. However, the problem here—whether we are discussing the reports of mystics of the past or of ‘psychonauts’ of the present—is that an attributional assessment offers no explanation for what is consistently reported as unity with an ultimate or absolute ‘Something.’ In this regard, Taves has herself commented that, “While an attributional approach does not need to agree that subjects actually had an immediate apprehension of the Absolute, researchers do need to provide a plausible explanation of why subjects felt as if they did” (ibid., p. 91).

I believe Huxley would have agreed with both Sjostedt-Hughes and Taves. Interpretations should be kept open and flexible to accommodate new information and alternate explanations, but they do qualitatively matter to people, conferring higher or lower levels of meaning. In addition, I see no reason why those experiencing UMEs should not entertain the possibility that they have actually experienced a ‘Something’ of the absolute sort, for instance Huxley’s “Mind-at-Large,” William James’s “mother sea of consciousness,” Meister Eckhart’s “Godhead,” Paul Tillich’s “Divine Ground of Being,” Ralph Waldo Emerson’s “Over-Soul” or some other absolute.

We currently live in a time when physicalism has invaded the humanities to such an extent that its philosophical viewpoint has been nearly accepted as settled opinion—including its view that the brain wholly generates what we call consciousness. But as Alfred North Whitehead once observed, “Every scientific man in order to preserve his reputation has to say he dislikes metaphysics. What he means is he dislikes having his metaphysics criticized” (cited in Henning et al. 2021, p. 128). We have no compulsion today to accept a physicalist view of consciousness and its relationship to the world, nor toward believing that the psyche cannot experience union with an Absolute.

We now have academic philosophers who can easily go toe-to-toe with physicalists, contradicting their position on the nature of consciousness. Bernardo Kastrup’s “analytic idealism,” Philip Goff’s “panpsychism,” Donald Hoffman’s “conscious realism,” David Chalmers’ “naturalistic dualism,” and other viewpoints stand in opposition to physicalism (e.g., as argued by Daniel Dennett, David Papineau, etc.), and, significantly, they do so without contradicting any scientific facts. For instance, regarding consciousness itself, physicalists take the position that it is wholly generated by the brain, but this is far from being a recognized fact, and many (including Huxley [1954] 1970, pp. 22–24), have argued that consciousness exceeds the brain, with the brain acting more like a filter, receiver, or contextualizer of consciousness existing beyond it.

The point that physicalism has not been established was made clear recently when Christof Koch, a neurologist and cognitive scientist, lost a long-standing bet with philosopher David Chalmers. In 1998, Koch had bet Chalmers that twenty-five years hence neuroscience would have solved Chalmers’ “hard problem of consciousness” by proving that the brain wholly generates consciousness. But in 2023, Koch had to admit that no such proof had come forward. Correlation between brain states and subjective experiences is undeniable, but correlation—as every student of philosophy knows—is not proof of causation, and causation has not been established. Consequently, the ultimate nature of consciousness, and its relationship to the brain, still remains a mystery. Koch owed Chalmer’s a case of expensive wine, and Huxley’s theory that mystics experience a level of consciousness beyond the individual remains a viable possibility—a possibility that may deliver great meaning and value.

6. Conclusions

This essay began with the observation that studies in comparative mysticism have largely excluded serious attention to the existence of similarities between the traditions for more than forty years. However, the paper argues, elements of similarity are easily identified in the primary literature, and specifically exist with regard to unitive-type mystical experiences of oneness with or absorption into an absolute principle (e.g., the Sacred, the Ground of Being, Ultimate Reality, God, etc.). In addition, and for that reason, what Aldous Huxley termed the “unitive knowledge” has featured prominently in the secondary sources dealing with mystical experience. Huxley did not see this experience as the ‘core’ or ‘essence’ of either religion or mysticism, as Steven T. Katz and others have claimed, but rather simply as one of several common threads running across the various traditions. And given that analysis suggests that this cross-cultural similarity may indeed exist, the paper supports the position that this similarity, and others as well, are deserving of closer analysis. Having argued this point, the essay then focuses on unitive experiences currently reported in psychedelic studies, lending support to Huxley’s view that some psychedelic experiences may register as meaningful and life-changing in ways indistinguishable from unitive experiences tracked in the traditional literature of mysticism. The paper argues that the increase in this type of experience, arising from the so-called ‘psychedelic renaissance,’ may be valuable to human happiness and then traces Huxley’s reasons for why this may be the case. The paper ends with an addendum citing support for Huxley’s view that unitive experiences may indeed be of connection with a ‘Something’ of the absolute or ultimate sort, rather than simply states of mind exclusively generated by the physical brain.