Dzogchen teacher, Alan Wallace, from his book “Meditations of a Buddhist Skeptic”: “Who has ever observed this physical reality—composed of matter, energy, space, and time—that objectively exists independently of all subjective sensory appearances? If we closely apply mindfulness to the immediate contents of our sensory experience, we perceive only appearances. If we recognize that in the seen there is only the seen, in the heard only the heard, and so on, we see that these appearances arise in the space of our minds as qualia, without physical attributes. The colors we see—as opposed to the frequencies of photons to which they correspond in the objective world—are not composed of matter or energy and do not exist in physical space, independent of awareness. Visual qualia have no mass, charge, or momentum—they have no physical attributes at all. This is also true of the sounds we hear, as opposed to physical sound waves that strike the eardrum; the smells we experience, as opposed to molecules suspended in the air; the tastes we experience, as opposed to the molecular components of our food; and the tactile sensations we feel, as opposed to electrochemical processes in the body. In short, all that we immediately experience in our own bodies and the world around us consists of appearances to our five senses, but none of these appearances has physical qualities. We conceptually assign the attributes of mass, electrical charge, momentum, and so forth to physical objects and processes that occur invisibly and independently of our sensory impressions. In other words, the real, absolutely objective physical world existing independently of our perceptions—including all scientific measurements and observations—is one that we know only conceptually. From a radically empirical perspective, all that we know by way of direct perception consists of appearances to our own minds. These appearances are not composed of matter or energy and have no location in objective space independent of awareness, because they are not physical. The very existence of an absolutely real, objective, physical universe is something that we can know only by means of rational inference. But how compelling is this so-called inference? In modern terms, the objective universe is a kind of “black box,” whose interior we can never inspect to see what’s really inside. We can observe only appearances allegedly produced by an unseen reality. The colors we see, for instance, are said to be generated in part by electromagnetic fields interacting with the retina, which then catalyzes a series of electrochemical events in the optic nerve and the visual cortex. But we never perceive electromagnetic fields themselves, nor do we perceive the retina, optic nerve, or brain, even though we may acquire impressions of these phenomena either through “direct” observation or via computer-generated imagery. We are attempting to causally infer the existence of physical entities and processes on the basis of their nonphysical effects, namely our sensory representations of them. But without knowing the actual nature of any physical entity as it exists from its own side, independent of our observations and measurements, we are in no position to determine how closely our sensory appearances “re-present” reality. We can never compare our experience to what exists independent of it—there is no way of poking into the black box of the objective physical world. The assumption we have been maintaining is that such an independent physical world must exist, for without it, there would be no explanation for the commonality and replicability of our experience of the world around us. We collectively look at the sky and see the same stars, planets, sun, and moon, all moving through space while the Earth spins, whether or not anyone is looking. Likewise, stars form and collapse independently of our observations of them. But is this the only possible explanation? According to Buddhist epistemology, it is possible to infer the existence of a cause on the basis of its effects only if one can observe the cause and determine that it uniquely causes the inferred effect. For example, one can infer the existence of fire on the basis of the presence of smoke only if one has already observed fire itself and knows that it alone is capable of producing smoke. If one were never able to observe fire or its production of smoke, one could not causally infer the existence of fire on the basis of observing smoke. For smoke might be produced by something else entirely, something unimaginable. Likewise, we have been assuming that the commonality of our experience of the world around us must be due to the fact that the appearances we perceive are representations of physical things and events that exist independently of experience. But how can we assume that the universe as it exists independently of our perceptions and thoughts corresponds to our human concept of “physical”? The very notion of physicality has evolved together with the evolution of modern physics, and it now includes such invisible, undetectable entities as dark matter and dark energy, which are said to constitute most of the physical universe. But since no one can observe any physical entity as it exists in itself, no one can guarantee that physical entities alone generate our subjective experience of the world. In short, to be a radical empiricist—in the seen to acknowledge just the seen—compels us to question the fundamental metaphysical assumption that underlies virtually all of modern science: the necessary existence of a physical world prior to and independent of consciousness. From a radically empirical perspective, all that we truly know is the reality of our own awareness and the sensory and mental appearances that arise to it. Whatever exists independently of these appearances is unknowable in principle, and there are no grounds for attributing existence to something that can never be known. Most of modern science—with the exception of quantum physics—is based on the metaphysical assumption that scientific theories “re-present” the objective, physical, quantifiable world that is really out there, independent of all our measurements and observations. But this assumption demonstrates a limited imagination that asserts that the commonality of experience can be explained only by invoking the existence of such an invisible and ultimately unknowable physical universe. In fact, all that we actually know is the mind and its appearances—they are all that we can confidently claim to exist. This is one assertion of the Yogachara, or Chittamatra (“ mind-only”) school of Buddhism, which is a form of philosophical idealism. Instead of adopting the materialist stance that physical reality is ultimately real and mental phenomena are emergent properties of physical processes, radical empiricism leads us to the opposite view: only the mind and its appearances are ultimately real; the so-called physical world is nothing more than a conceptual construct superimposed on nonphysical sensory appearances. This means that the materialist assumption behind scientific discoveries concerning the nature of objective reality independent of appearances is simply a pervasive delusion. An absolutely objective physical world doesn’t exist at all, and any statement about what occurs independent of appearances is fictitious. This conclusion has also been reached by some contemporary quantum physicists. How then shall we account for the commonality of our experience? It is not only humans who perceive and interact with the physical world but also animals, however different our perceptions and interpretations may be. We can explain the consensual nature of our experience as resulting from the fundamental role of the mind in nature and the profound entanglement of the individual mind-streams of sentient beings inhabiting the universe. Such a hypothesis might seem shocking to those of us accustomed to revering science as the most authoritative method for exploring reality. But reliance upon objective, quantitative measures is a very recent trend in human history; it became globally dominant only in the twentieth century. When one’s awareness becomes immersed in this radically empirical approach to the investigation of the mind, it is easy to reach the conclusion that the mind alone is real. As William James so cogently declared, “for the moment, what we attend to is reality.” If an individual or society focuses all attention on physical reality, this is certain to be taken as exclusively real; and if all attention is focused single-pointedly on the mind and its appearances, this too will be taken as exclusively real. This “mind-only” conclusion is not derived on the basis of logical reasoning alone; instead, it requires a combination of experiential, contemplative inquiry into the nature of the mind and its relation to the world of the physical senses together with the use of reason to make sense of one’s observations. This is a rational conclusion based upon empirical investi gations using contemplative science rather than materialistic science as we know it today. The culmination of such contemplative inquiry is not merely the intellectual formulation of a philosophical position, but rather an immediate, nonconceptual experience of the nonduality of subject and object. Appearances are directly perceived to be empty of any external, independent reality, physical or otherwise. In the seen, there is only the seen, in the heard, only the heard, in the felt, only the felt, and in the mentally cognized, only the mentally cognized. When we come to this direct realization, we perceive reality for the first time as it actually is, consisting only of the mind and its appearances, arising nondually from moment to moment. Appearances are ungrounded in any other reality—not in matter, energy, space, or time. We experience appearances nakedly, for they are not “re-presentations” of anything else. They are what they are, and the sense of a reified bifurcation into self and other, or subject and object, vanishes. As a result, we attain freedom from a range of subtle mental afflictions and obscurations that arise in dependence upon the delusion that grasps onto an absolute distinction between subject and object. This is a true revolution in our understanding and experience of the natural world, and it destroys the very foundations of virtually all of modern science, with the exception of the most fundamental branch of physics, quantum mechanics. MADHYAMAKA: ONTOLOGICAL RELATIVISM The preceding application of radical empiricism and logical reasoning leads to the conclusion that only the mind, together with its emergent appearances, is real. Within the field of experience, we continue to identify a class of phenomena as physical—from subatomic particles up to galactic clusters—but they have no external existence independent of the mind. Such physical entities have only conventional existence. To the delusional, dualistic mind, even without conscious labeling, physical objects appear to be already existent as the referents of their names. In other words, even before we verbally or conceptually identify the entities that objectively appear to us, we have a sense that they are already awaiting the labels we impute upon them. This assumption that entities are self-defining affects every sentient being—even those who do not use language, such as animals and babies—and it is illusory. But in the same spirit of radical empiricism, we may investigate the nature of the mind itself: Is its appearance any less illusory than that of the physical world? Let us now turn the focus of our contemplative inquiry inward upon the very nature of the mind that observes phenomena and acts upon them. Materialists regard only the physical world and its emergent properties and functions as real; everything else is illusory. However, the preceding line of contemplative and philosophical inquiry led us to the conclusion that only the mind and its emergent properties and functions are real, everything else being illusory. The physical world, as something absolutely objective but hidden behind the veil of subjective appearances, turned out to have no basis in reality. What about the mind? When we seek to observe the mind itself—the source of emergent appearances and functions—is it anywhere to be found? Following the Buddha’s maxim, “in the cognized, there is only the cognized,” all that we actually experience are appearances and awareness; nowhere is a “mind” found apart from this flow of ever-changing appearances and awareness. Just as no inherently existent physical world is ever found that underlies appearances of the objective world, so there is no evidence of an inherently existent mind that underlies subjective experience. The very distinction between mind and appearances is purely nominal, and the more deeply we probe into the immediate contents of experience, the more clearly we perceive that appearances are as empty of inherently existent mind as they are of inherently existent matter. Both “matter” and “mind” are simply conceptual constructs imputed upon appearances; neither has any existence of its own, independent of these conceptual imputations. Just as the physical world has no inherent existence, independent of words and concepts, neither does the world of the mind have any inherent existence, independent of words and concepts. There is no real physical world existing independently “out there,” and there is no real mental world existing independently “in here.” We may now adjust our earlier translation of the Buddha’s instructions to Bahiya, replacing “you” with “thing,” referring to any inherently existing subject or object: ‘When for you there is only the seen in reference to the seen, only the heard in reference to the heard, only the felt in reference to the felt, only the cognized in reference to the cognized, then, Bahiya, there is no thing here. When there is no thing here, there is no thing there. When there is no thing there, things are neither here nor there nor between the two. This, just this, is the end of suffering.’ The very distinction between external and internal is purely conventional, having no existence apart from words and thoughts. Conventionally speaking, the physical world may indeed be said to exist independently of sensory appearances, and there are dimensions of consciousness that exist independently of any physical basis. But these external physical and internal mental phenomena do not inherently exist independently of conceptual designations. By recognizing the symmetry of the emptiness of physical and mental phenomena, objective and subjective, we avoid the philosophical extremes of both materialism and idealism. This is the Madhyamaka view. All phenomena exist only relative to the ways they are known. Perceptual appearances exist relative to perceptual experience, and conceived objects, such as elementary particles, energy, and space-time, exist relative to the minds that conceive them. These are all relative, or conventional, realities. Only the emptiness of inherent nature of all phenomena is ultimate. This is the sole invariant in all of nature. While abiding in nonconceptual meditative equipoise, directly realizing the emptiness of inherent existence of all things, we find that sensory appearances vanish into a spacelike vacuity. When we emerge from such meditation, appearances arise once again, but they now exhibit a dreamlike quality. Even though objects appear to exist from their own side, independently of words and concepts, we intuitively know that such appearances are illusory. Nothing during the waking state exists by its own inherent nature, from its own side, any more than appearances in a dream. As for the commonality of experience and the regularities of causal interactions that seem to occur independently of appearances, these can be understood by perceiving all phenomena arising as dependently related events, without any inherent basis in mind or matter. When we truly fathom this way of viewing reality without falling to philosophical extremes, we see that it is only because all phenomena are empty of inherent nature that they can causally interact, and insight into their dependently related mode of existence reveals their emptiness of inherent existence. This direct, nonconceptual, experiential insight uproots even the subtlest of mental afflictions and obscurations. THE GREAT PERFECTION: THE ONE TASTE OF PURITY AND EQUALITY Imagine that you are in the midst of a prolonged nonlucid dream, unaware that you are dreaming, and you devote yourself single-pointedly to the shamatha practice called settling the mind in its natural state. When you withdraw your awareness from all sensory appearances in the dream, all appearances dissolve into the substrate (alaya), and your dreaming mind dissolves into the substrate consciousness. Now imagine that you return to the dream and practice vipashyana, probing into the nature of all objective and subjective appearances. Finally, when you achieve a nonconceptual realization of the emptiness of inherent nature of all phenomena, all appearances again dissolve into the substrate, not because you have withdrawn your awareness from them but because your nonconceptual mind no longer imputes existence upon any of them. Your mind again dissolves into the substrate consciousness, but instead of apprehending the mere vacuity of the substrate, you directly realize the emptiness (Skt. shunyata) of all phenomena, also known as ultimate reality (Skt. dharmata), and the absolute space of phenomena (Skt. dharmadhatu). This is nirvana itself, and according to the Buddha, the phenomenal world of Samsara would not exist without it. Now imagine that you reactivate your conceptual mind and reengage with the world of appearances, which you clearly see to be dreamlike. Then suddenly it dawns on you that everything you are experiencing is not like a dream, it actually is a dream. Now you become lucid, “breaking through” your dreaming consciousness to waking consciousness, so that you are awake within the dream. You see that whatever occurs—both heavenly experiences and hellish ones—can neither harm nor benefit you. You perceive the “one taste of equal purity” concerning all that appears within the dream as well as the absence of appearances in the dreamless experience of the substrate. Being fully awake, you are not deluded into reifying things and events in the dream; nor is your mind withdrawn into the substrate. If you should display “supernormal abilities” and someone were then to ask you whether you are human, your reply would be, “No.” You are not anyone within the dream, human or otherwise. You are awake. Such was the Buddha’s reply when asked these questions about the nature of his identity. According to the view of the Great Perfection, the culmination of the path of radical empiricism occurs when we realize the nonduality of Samsara and nirvana, no longer bound within the miseries of the former yet not lost in the utter transcendence of the latter. For the first time, we are truly awake to the nature of the whole of reality manifesting as displays of the nonduality of primordial consciousness and the absolute space of phenomena. Now that we are perfectly awake to this Great Perfection, all that remains to be done is to awaken everyone else.”