Salut, I'm Julia.

To the extent I regard the experience as veridical—and about that I’m still not sure—it tells me that consciousness is primary to the physical universe. In fact, it precedes it.” Did he now believe consciousness exists outside the brain? He’s not certain. “But to go from being very sure that the opposite is true”—that consciousness is the product of our gray matter—“to be unsure is an immense shift.” I asked him if he agreed with something I’d read the Dalai Lama had said, that the idea that brains create consciousness—an idea accepted without question by most scientists—“is a metaphysical assumption, not a scientific fact.” “Bingo,” Jesse said. “And for someone with my orientation”—agnostic, enamored of science—“that changes everything.”

Richards emerged from those first psychedelic explorations in possession of three unshakable convictions. The first is that the experience of the sacred reported both by the great mystics and by people on high-dose psychedelic journeys is the same experience and is “real”—that is, not just a figment of the imagination. “You go deep enough or far out enough in consciousness and you will bump into the sacred. It’s not something we generate; it’s something out there waiting to be discovered. And this reliably happens to nonbelievers as well as believers.” Second, that, whether occasioned by drugs or other means, these experiences of mystical consciousness are in all likelihood the primal basis of religion. (Partly for this reason Richards believes that psychedelics should be part of a divinity student’s education.) And third, that consciousness is a property of the universe, not brains. On this question, he holds with Henri Bergson, the French philosopher, who conceived of the human mind as a kind of radio receiver, able to tune in to frequencies of energy and information that exist outside it.

The sheer suggestibility of psychedelics is one of their defining characteristics, so in one sense it is no wonder that so many of the first cohort of volunteers at Hopkins had powerful mystical experiences: the experiment was designed by three men intensely interested in mystical states of consciousness. (And it is likewise no wonder that the European researchers I interviewed all failed to see as many instances of mystical experience in their subjects as the Americans did in theirs.)

Compared with many scientists—or for that matter many spiritual types—Roland Griffiths possesses a large measure of what Keats, referring to Shakespeare, described as “negative capability,” the ability to exist amid uncertainties, mysteries, and doubt without reaching for absolutes, whether those of science or spirituality. “It makes no more sense to say I’m 100 percent convinced of a material worldview than to say I’m 100 percent convinced of the literal version of the Bible.”

So here was a curious paradox. The same phenomenon that pointed to a materialist explanation for spiritual and religious belief gave people an experience so powerful it convinced them of the existence of a nonmaterial reality—the very basis of religious belief.

...we are closer, genetically speaking, to the fungal kingdom than to that of the plants. Like us, they live off the energy that plants harvest from the sun.

...forest is a far more complex, sociable, and intelligent entity than we knew, and it is fungi that organize the arboreal society.

Defense against pests and diseases is the most common function of the so-called secondary metabolites produced in plants. Curiously, many plant toxins don’t directly kill pests, but often act as psychostimulants as well as poisons, which is why we use many of them as drugs to alter consciousness. Why wouldn’t plants just kill their predators outright? Perhaps because that would quickly select for resistance, whereas messing with its neurotransmitter networks can distract the predator or, better still, lead it to engage in risky behaviors likely to shorten its life. Think of an inebriated insect behaving in a way that attracts the attention of a hungry bird.

In fact Beug has tested fungi for psilocybin and psilocin levels and found that they occur only in minute quantities in the mycelium—the part of the organism most likely to be well defended. “Instead the chemicals are in the fruiting bodies—sometimes at over two percent by dry weight!”—a stupendous quantity, and in a part of the organism it is not a priority to defend.

Eaten in small doses, psychedelic mushrooms might well increase fitness in animals, by increasing sensory acuity and possibly focus as well.

Samorini calls this a “depatterning factor.” There are times in the evolution of a species when the old patterns no longer avail, and the radical, potentially innovative perceptions and behaviors that psychedelics sometimes inspire may offer the best chance for adaptation. Think of it as a neurochemically induced source of variation in a population. It is difficult to read about Samorini’s lovely theory without thinking about our own species and the challenging circumstances in which we find ourselves today. Homo sapiens might have arrived at one of those periods of crisis that calls for some mental and behavioral depatterning. Could that be why nature has sent us these psychedelic molecules now?

The modern conceit of the scientist attempting to observe nature with perfect objectivity, as if from a vantage located outside it, would have been anathema to Humboldt. “I myself am identical with nature.”

Instead of seeing nature as a collection of discrete objects, the Romantic scientists—and I include Stamets in their number—saw a densely tangled web of subjects, each acting on the other in the great dance that would come to be called coevolution. “Everything,” Humboldt said, “is interaction and reciprocal.”

Not quite a hallucination, “projection” is probably the psychological term for this phenomenon: when we mix our emotions with certain objects that then reflect those feelings back to us so that they appear to glisten with meaning.

Nature does in fact teem with subjectivities—call them spirits if you like—other than our own; it is only the human ego, with its imagined monopoly on subjectivity, that keeps us from recognizing them all, our kith and kin.

Psychologists call these self-fulfilling prophecies “expectancy effects,” and they turn out to be especially powerful in the case of psychedelics.

...the psychotomimetic paradigm was replaced not by one but by two distinct new theoretical models: the psycholytic and, later, the psychedelic model.

“I’ve had my ego stripped away. A man is a better actor without ego, because he has truth in him. Now I cannot behave untruthfully toward anyone, and certainly not to myself.” From the sound of it, LSD had turned Cary Grant into an American.

If the period we call “the 1960s” actually began sometime in the 1950s, the fad for LSD therapy that Cary Grant unleashed in 1959 is one good place to mark a shift in the cultural breeze. Years before Timothy Leary became notorious for promoting LSD outside a therapeutic or research context, the drug had already begun “escaping from the lab” in Los Angeles and receiving fervent national press attention.

Sounding a theme that would crop up repeatedly in the history of psychedelic research, Cohen struggled with the tension between the spiritual import of the LSD experience (and the mystical inclinations it brought out in its clinical practitioners) and the ethos of science to which he was devoted. He remained deeply ambivalent.

...it takes psychotherapy perilously close to the world of shamanism and faith healing, a distinctly uncomfortable place for a scientist to be. And yet as long as it works, as long as it heals people, why should anyone care? (This is the same discomfort scientists feel about using placebos. It suggests an interesting way to think about psychedelics: as a kind of “active placebo,” to borrow a term proposed by Andrew Weil in his 1972 book, The Natural Mind. They do something, surely, but most of what that is may be self-generated. Or as Stanislav Grof put it, psychedelics are “nonspecific amplifiers” of mental processes.)

For Huxley, the drug gave him unmediated access to realms of existence usually known only to mystics and a handful of history’s great visionary artists. This other world is always present but in ordinary moments is kept from our awareness by the “reducing valve” of everyday waking consciousness, a kind of mental filter that admits only “a measly trickle of the kind of consciousness” we need in order to survive.

Bergson believed that consciousness was not generated by human brains but rather exists in a field outside us, something like electromagnetic waves; our brains, which he likened to radio receivers, can tune in to different frequencies of consciousness.

How much does the idea of cyberspace, an immaterial realm where one can construct a new identity and merge with a community of virtual others, owe to an imagination shaped by the experience of psychedelics? Or for that matter virtual reality? The whole notion of cybernetics, the idea that material reality can be translated into bits of information, may also owe something to the experience of LSD, with its power to collapse matter into spirit.

In 1960, the future of psychedelic research looked bright. Yet within the brief span of five years, the political and cultural weather completely shifted, a moral panic about LSD engulfed America, and virtually all psychedelic research and therapy were either halted or driven underground. What happened? “Timothy Leary” is the too-obvious answer to that question.

Leary did do some original work theorizing the idea of “set” and “setting,” deploying the words in this context for the first time in the literature. These useful terms, if not the concepts they denote—for which Al Hubbard deserves most of the credit—may well represent Leary’s most enduring contribution to psychedelic science.

As with Hubbard and Huxley and Osmond before him, psychedelics had convinced Leary that they had the power not just to heal people but to change society and save humankind, and it was his mission to serve as their prophet. It was as though the chemicals themselves had hit upon a brilliant scheme for their own proliferation, by colonizing the brains of a certain type of charismatic and messianic human.

Two years after his departure from Harvard, Alpert embarked on a spiritual journey to India and returned as Ram Dass.

Beginning with Allen Ginsberg’s December 1960 psilocybin trip at his house in Newton, Leary forged a link between psychedelics and the counterculture that has never been broken and that is surely one of the reasons they came to be regarded as so threatening to the establishment. (Could it have possibly been otherwise? What if the cultural identity of the drugs had been shaped by, say, a conservative Catholic like Al Hubbard?

What doomed the first wave of psychedelic research was an irrational exuberance about its potential that was nourished by the drugs themselves—that, and the fact that these chemicals are what today we would call disruptive technologies. For people working with these powerful molecules, it was impossible not to conclude that—like that divinity student running down Commonwealth Avenue—you were suddenly in possession of news with the power to change not just individuals but the world.

So maybe this, then, is the enduring contribution of Leary: by turning on a generation—the generation that, years later, has now taken charge of our institutions—he helped create the conditions in which a revival of psychedelic research is now possible.

So rather than starting from scratch to build a new perception from every batch of raw data delivered by the senses, the mind jumps to the most sensible conclusion based on past experience combined with a tiny sample of that data. Our brains are prediction machines optimized by experience, and when it comes to faces, they have boatloads of experience: faces are always convex.

The journeys have shown me what the Buddhists try to tell us but I have never really understood: that there is much more to consciousness than the ego, as we would see if it would just shut up. And that its dissolution (or transcendence) is nothing to fear; in fact, it is a prerequisite for making any spiritual progress.

But the ego, that inner neurotic who insists on running the mental show, is wily and doesn’t relinquish its power without a struggle. Deeming itself indispensable, it will battle against its diminishment, whether in advance or in the middle of the journey.

So perhaps spiritual experience is simply what happens in the space that opens up in the mind when “all mean egotism vanishes.” Wonders (and terrors) we’re ordinarily defended against flow into our awareness; the far ends of the sensory spectrum, which are normally invisible to us, our senses can suddenly admit. While the ego sleeps, the mind plays, proposing unexpected patterns of thought and new rays of relation. The gulf between self and world, that no-man’s-land which in ordinary hours the ego so vigilantly patrols, closes down, allowing us to feel less separate and more connected, “part and particle” of some larger entity. Whether we call that entity Nature, the Mind at Large, or God hardly matters. But it seems to be in the crucible of that merging that death loses some of its sting.

Carhart-Harris and his colleagues had discovered that psilocybin reduces brain activity, with the falloff concentrated in one particular brain network that at the time he knew little about: the default mode network. The network forms a critical and centrally located hub of brain activity that links parts of the cerebral cortex to deeper (and older) structures involved in memory and emotion.

...the brain’s “default mode,” the network of brain structures that light up with activity when there are no demands on our attention and we have no mental task to perform. Put another way, Raichle had discovered the place where our minds go to wander.

Perhaps the most striking discovery of Carhart-Harris’s first experiment was that the steepest drops in default mode network activity correlated with his volunteers’ subjective experience of “ego dissolution.”

The mystical experience may just be what it feels like when you deactivate the brain’s default mode network. This can be achieved any number of ways: through psychedelics and meditation, as Robin Carhart-Harris and Judson Brewer have demonstrated, but perhaps also by means of certain breathing exercises (like holotropic breathwork), sensory deprivation, fasting, prayer, overwhelming experiences of awe, extreme sports, near-death experiences, and so on.

...brain scans show an increase in activity (as reflected by increases in blood flow and oxygen consumption) in several other brain regions, including the limbic regions, under the influence of psychedelics. This disinhibition might explain why material that is unavailable to us during normal waking consciousness now floats to the surface of our awareness, including emotions and memories and, sometimes, long-buried childhood traumas.

But the default mode network doesn’t only exert top-down control over material arising from within; it also helps regulate what is let into consciousness from the world outside. It operates as a kind of filter (or “reducing valve”) charged with admitting only that “measly trickle” of information required for us to get through the day. If not for the brain’s filtering mechanisms, the torrent of information the senses make available to our brains at any given moment might prove difficult to process—as indeed is sometimes the case during the psychedelic experience.

As a psychonaut acquaintance put it to me, “If it were possible to temporarily experience another person’s mental state, my guess is that it would feel more like a psychedelic state than a ‘normal’ state, because of its massive disparity with whatever mental state is habitual with you.” Another trippy thought experiment is to try to imagine the world as it appears to a creature with an entirely different sensory apparatus and way of life. You quickly realize there is no single reality out there waiting to be faithfully and comprehensively transcribed.

“spectrum of cognitive states,” ranging from high-entropy mental states to low ones. At the high-entropy end of the spectrum, he lists psychedelic states; infant consciousness; early psychosis; magical thinking; and divergent or creative thinking. At the low-entropy end of the spectrum, he lists narrow or rigid thinking; addiction; obsessive-compulsive disorder; depression; anesthesia; and, finally, coma. Carhart-Harris suggests that the psychological “disorders” at the low-entropy end of the spectrum are not the result of a lack of order in the brain but rather stem from an excess of order.

But when the brain operates under the influence of psilocybin, as shown on the right, thousands of new connections form, linking far-flung brain regions that during normal waking consciousness don’t exchange much information. In effect, traffic is rerouted from a relatively small number of interstate highways onto myriad smaller roads linking a great many more destinations. The brain appears to become less specialized and more globally interconnected, with considerably more intercourse, or “cross talk,” among its various neighborhoods.

Being inexperienced in the way of the world, the mind of the young child has comparatively few priors, or preconceptions, to guide her perceptions down the predictable tracks. Instead, the child approaches reality with the astonishment of an adult on psychedelics.

In teaching computers how to learn and solve problems, AI designers speak in terms of “high temperature” and “low temperature” searches for the answers to questions. A low-temperature search (so-called because it requires less energy) involves reaching for the most probable or nearest-to-hand answer, like the one that worked for a similar problem in the past. Drawing on its wealth of experience, the adult mind performs low-temperature searches most of the time.

Gopnik believes that both the young child (five and under) and the adult on a psychedelic have a stronger predilection for the high-temperature search; in their quest to make sense of things, their minds explore not just the nearby and most likely but “the entire space of possibilities.”

...the great gift of the psychedelic journey, especially to the dying: its power to imbue everything in our field of experience with a heightened sense of purpose and consequence. Depending on one’s orientation, this can be understood either in humanistic or in spiritual terms—for what is the Sacred but a capitalized version of significance?

But when we are able to visualize our thoughts—such as the thought of ourselves as a smoker looking like a coughing gargoyle—those thoughts take on added weight, feel more real to us. Seeing is believing. Perhaps this is one of the things psychedelics do: relax the brain’s inhibition on visualizing our thoughts, thereby rendering them more authoritative, memorable, and sticky.

Addiction is, among other things, a radical form of selfishness. One of the challenges of treating the addict is getting him to broaden his perspective beyond a consuming self-interest in his addiction, the behavior that has come to define his identity and organize his days. Awe, Hendricks believes, has the power to do this.

Depression is a response to past loss, and anxiety is a response to future loss.” Both reflect a mind mired in rumination, one dwelling on the past, the other worrying about the future. What mainly distinguishes the two disorders is their tense.

The therapeutic value of psychedelics, in Carhart-Harris’s view, lies in their ability to temporarily elevate entropy in the inflexible brain, jolting the system out of its default patterns. Carhart-Harris uses the metaphor of annealing from metallurgy: psychedelics introduce energy into the system, giving it the flexibility necessary for it to bend and so change.

And then there is the ego, perhaps the most formidable creation of the default mode network, which strives to defend us from threats both internal and external. When all is working as it should be, the ego keeps the organism on track, helping it to realize its goals and provide for its needs, notably for survival and reproduction. It gets the job done. But it is also fundamentally conservative.

The usual antonym for the word “spiritual” is “material.” That at least is what I believed when I began this inquiry—that the whole issue with spirituality turned on a question of metaphysics. Now I’m inclined to think a much better and certainly more useful antonym for “spiritual” might be “egotistical.” Self and Spirit define the opposite ends of a spectrum, but that spectrum needn’t reach clear to the heavens to have meaning for us. It can stay right here on earth. When the ego dissolves, so does a bounded conception not only of our self but of our self-interest. What emerges in its place is invariably a broader, more openhearted and altruistic—that is, more spiritual—idea of what matters in life. One in which a new sense of connection, or love, however defined, seems to figure prominently.

Buddhists believe that attachment is at the root of all forms of mental suffering; if the neuroscience is right, a lot of these attachments have their mooring in the PCC, where they are nurtured and sustained. Brewer thinks that by diminishing its activity, whether by means of meditation or psychedelics, we can learn “to be with our thoughts and cravings without getting caught up in them.”

To us, we are the world’s only conscious subjects, with the rest of creation made up of objects; to the more egotistical among us, even other people count as objects. Psychedelic consciousness overturns that view, by granting us a wider, more generous lens through which we can glimpse the subject-hood—the spirit!—of everything, animal, vegetable, even mineral, all of it now somehow returning our gaze. Spirits, it seems, are everywhere. New rays of relation appear between us and all the world’s Others.