As this excerpt from Science and Philosophy in the Indian Buddhist Classics, Volume 2: The Mind reveals, Buddhist understandings of consciousness can be complex — but consciousness itself is perfectly luminous.
In general, mind or consciousness refers to inner experience. This includes feelings that are pleasant or painful, states of mind that are happy or miserable, emotional experiences such as fear of danger, anger toward those who inflict harm, affectionate attachment to close relatives, and compassion when observing suffering sentient beings. It includes sense consciousness—such as a visual consciousness that sees a vase filled with beautiful flowers, or an auditory consciousness that hears the sounds of music or singing. It also includes cognitions that remember previous experiences, as in “I remember this” or “I thought this,” and cognitions that consider reasons and think “If this is the case, then that must also be the case,” and so on. Whatever position one holds—that the mind is material or immaterial—in general what we call consciousness is known to exist based on experience, so it does not necessarily need to be proved through reasoning. Nevertheless, there are many types of subtle mental states that must be proved through reasoning.
Someone may ask, “What is the difference between consciousness and physical things?” In general, matter and consciousness are differentiated by whether they are obstructive, established as clear and aware in nature, merely experiential in nature, and capable of knowing objects. Many earlier Buddhist masters identify the essential nature of consciousness as the opposite of obstructive physical things: lacking obstructivity, consciousness has the quality of clarity (in that external and internal things can appear to it), it has the quality of knowing its object, and it has the nature of mere experience.
Both happiness and suffering finally depend on the functioning of the mind.
Thus, when identifying the nature of the mind, the sutras teach that the mind is difficult to catch hold of: being intangible, it is weightless; like a firebrand spinning around, it does not rest; like the constantly moving waves of the ocean, it is unstable; like a forest fire, it ignites all deeds of body and speech; like a great river, the mind forcefully draws along a vast number of internal movements of awareness; and so forth.
In general, the mind is the main factor involved in accomplishing the goals that living beings desire. The mind, unlike physical things, is difficult to identify. Yet if we train our mind, then in reliance on mindfulness, meta-awareness, heedfulness, and so on, we will attain both temporary and final happiness. Therefore, in the Buddhist tradition, the system of analyzing the mind in great detail flourished from the earliest times. This is also the main reason why Buddhist texts have extensive explanations about psychology. For example, in the Buddha’s own Dhammapada it states:
Do not commit any evil,
practice supreme virtue,
thoroughly tame your own mind;
this is the teaching of the Buddha.
Both the happiness and suffering that arise in relation to beings’ desired goals finally depend on the functioning of the mind—for it is owing to the force of having one’s mind tamed or not tamed that temporary or lasting happiness and suffering arise. The essence of the Buddha’s teaching is said to be the thorough taming of the mind.
Generally, in the context of Buddhist texts, the terms cognition (which is the translation of the Sanskrit word buddhi), consciousness (the translation of jnana), and awareness (the translation of samvitti) are all treated as coextensive or synonymous. The nature of cognition is stated to be awareness, and the nature of consciousness is said to be clear (or luminous) and aware. “Clear” here expresses the essential nature of consciousness, and “aware” expresses its function. “Clear” also indicates: (1) that consciousness is beyond the nature of matter, which is characterized as tangible and obstructive, so it is clear in nature; (2) that just as reflections appear in a mirror, any internal or external object whatsoever—good or bad, pleasant or unpleasant—can appear in consciousness, so consciousness is luminous in that it illuminates objects; and (3) that the essential nature of consciousness is not contaminated by the stains of mental afflictions such as attachment, so its nature is clear or luminous. Thus, several meanings of the word clear are stated in the texts.
That consciousness is devoid of the property of obstructivity is explicitly stated in the sutras. For example, the Teaching on the Undifferentiated Nature of the Sphere of Reality says: “Is this mind blue? Is it yellow?” Also, the Chapter on the Thirty-Three says: “The mind has no form, it cannot be pointed out, it has no obstructivity, and it is not representable.” Passages such as these explain how the mind lacks color and shape, cannot be visually pointed out, and has no obstructivity.
As noted above, consciousness is posited to be luminously clear in that any internal or external object whatsoever—good or bad, pleasant or unpleasant—can appear in it. This is explained as follows. Just as sunlight or electric light illuminates forms, any external or internal phenomena can be illuminated by—that is, they can appear to—consciousness; it is what makes objects known or manifest. Yet the illumination of sunlight or electric light and the “luminous clarity” that is the essential nature of consciousness are utterly dissimilar, for sunlight and electric light illuminate only what is in their immediate vicinity and cannot illuminate other things. The way that consciousness illuminates objects is not restricted in that way.
Many Buddhist scriptures teach that afflictions such as attachment present within the mind are adventitious, and that the nature of the mind is luminous clarity. For example, a sutta of the Theravada school in the Numerical Discourses says: “O bhikkhus, this mind of luminous clarity is afflicted due to adventitious afflictions. Ordinary beings who have not heard this do not thoroughly understand reality just as it is. Therefore, not having heard, ordinary beings do not cultivate their minds. Thus I have spoken.” The Perfection of Wisdom Sutra in Eight Thousand Lines says: “Thus this mind is devoid of mind, for the mind’s nature is luminous clarity.”
The Buddha Nature Sutra says:
Just as where the most precious gold exists,
one completely purifies it then makes use of it,
likewise, I see all sentient beings continuously
being harmed for a long time by mental afflictions,
so I teach the dharma as a means to purify
the nature of what are “adventitious afflictions.”
Among the treatises, Maitreya’s Sublime Continuum says:
Like the purity of a jewel, space, or water,
it is always undefiled in nature.
Just as the nature of gold is not rusted, the nature of space is not clouded, and the nature of water is not muddied, so the nature of the mind is not stained. The same text states:
The luminously clear nature of the mind
is unchanging, like space, because
it does not become defiled by adventitious stains,
attachment, and so on, which arise from an improper way
That is, just as empty space does not change by virtue of being inside different containers, so the ultimate nature of the mind, which is merely the lack of true existence of the mind, cannot change into something else on account of the afflictions such as attachment, which are adventitious stains. According to this text, therefore, the “nature of the mind” is the absence of true existence of the mind; and the meaning of “adventitious stains” is that they do not exist truly as the essential nature of the mind, which is luminously clear and aware. Moreover, if the stains within the mind were truly existent, they would have to exist without depending on anything; hence, it would be impossible to remove them from the mind by cultivating their antidotes. However, since they lack true existence, it is possible to generate antidotes for the stains and remove them from the mind.
Dharmakirti says in his Exposition of Valid Cognition:
The nature of the mind is luminous clarity;
the stains are adventitious.
The stains of attachment and so on, which are the basic causes that give rise to suffering, can be removed in reliance on their antidotes; and since those stains do not impinge on the nature of the mind, the nature of the mind is luminous clarity, as discussed above.
Also, according to one interpretation, the line “The nature of the mind is luminous clarity” points to the fact that, just as reflections appear in a mirror, the quality of consciousness is that internal and external objects can appear to it. Moreover, those who accept reflexive awareness interpret the luminous clarity of mind as not just meaning that moments of consciousness illuminate their objects; instead, consciousness also illuminates itself, which is to say that it is by its very nature self-luminous.
Exposition of Valid Cognition says:
Therefore, according to us, the mind itself is luminous,
since it is by nature luminous clarity;
and something else [namely, an object] is also luminous
in that it is illuminated by projecting its form into the mind.
The mind, the subjective, is luminous because it is by nature itself luminous clarity. Something else, namely an object such as a visible form, becomes the appearing object of that consciousness by means of something like the transference of its image—that is, visible form and so on—into that luminously clear consciousness. Therefore it is said that forms and so on clearly appear to that consciousness. In that case, consciousness has both the quality of illuminating, in the sense of being illuminating itself, and the quality of illuminating its object, in the sense that the image of the object appears. In some contexts, when “luminously clear” and “aware” are discussed, the mind may be additionally called “empty” in the sense of being naturally empty of obstructivity, for those texts identify the nature of consciousness as having three qualities—emptiness, luminous clarity, and awareness.
The second quality of consciousness mentioned above is awareness, which expresses the function of consciousness. Exposition of Valid Cognition says:
Consciousness has the attribute of apprehending its object;
it apprehends it in the way that it exists;
and by virtue of being existent, the nature of the object
is to produce consciousness.
Consciousness apprehends its object or operates by way of cognizing its object, which must indicate that the foremost unique attribute of consciousness is to apprehend its object or to cognize its object.
Santaraksita speaks about the essential nature of consciousness in terms of having the quality of cognizing its own nature, which is the opposite of the nature of matter or something having a material form. Ornament for the Middle Way says:
Consciousness arises in a way that is opposite
to anything in the nature of matter;
that which is nonmaterial in nature
is that which knows its own nature.
In the Ornament for the Middle Way Autocommentary related to this stanza, it says:
First, according to those who posit consciousness to be without a dualistic image [of object and subject], consciousness does not meet with an appearance of its object but is involved merely in cognizing itself. This means that, by its nature, it cannot experience an object other than itself. Consciousness is thus posited to have the nature of reflexive awareness because it is itself luminously clear by nature and because it is opposite to the nature of chariots and so on, which lack awareness. Since consciousness is reflexively aware of itself, it does not depend on some other cognizer [for consciousness itself to be known], unlike the case of blue and so on. Thus what we mean by awareness is that it is not unaware.
As for the meaning of those passages, Kamalasila’s Commentary on Difficult Points of the Ornament for the Middle Way says: “The concise meaning is as follows. The functioning of reflexive awareness is the very opposite of the nature of material things, such as chariots or groups of parts; that is, awareness does not depend on any other illuminator [in order to occur]; and with that function in place, one thus engages in activities.”
According to a literal reading of Santaraksita’s root text and commentary and Kamalasila’s Commentary on Difficult Points of the Ornament for the Middle Way, they both uphold the position asserting reflexive awareness, in that they explain the essential nature of consciousness to be the opposite of physical phenomena. However, even according to those who do not accept the notion of “reflexive awareness,” Santaraksita’s reasoning, from a general point of view, points to a hugely important difference between matter and consciousness. For example, to know something physical such as a red lotus flower or, to use Santaraksita’s example, something external such as a chariot, it must depend on some other nonphysical phenomenon, namely, consciousness. Thus, in general, whereas consciousness can be aware of consciousness, a physical thing cannot be aware of a physical thing. Therefore obstructive physical phenomena do not have the quality of knowing objects.
If, in general, matter and consciousness are fundamentally different with respect to their essential natures—in such terms as whether they are obstructive, exist by nature as clear and cognizing, and are in the nature of mere experience—then the question arises, which of these two must be considered fundamental in reality? Also, what is the nature of the relationship between matter and consciousness? Now the proponents of the Carvaka ancient Indian philosophical school posit physical phenomena to be fundamental and inner mental phenomena to be mere attributes of physical phenomena—like the shadow of a physical object, like the light of an oil lamp, or like the potency of beer. However, the general position of classical Buddhist thinkers is that material phenomena and consciousness are equally fundamental in reality. They maintain that just as physical phenomena cannot be reduced ultimately to some kind of substance or stuff of consciousness, likewise mental phenomena cannot be reduced ultimately to some kind of material substance such as the subtle elements.
Furthermore, although anything that is not consciousness, such as something physical, cannot be the substantial cause of consciousness, both matter and consciousness are mutually dependent on each other. Hence one must definitely accept that the two have a cooperative causal relationship. It is very clear, for example, that the sense consciousnesses would not arise without their causal bases, the physical sense organs. Also, most types of mental consciousness, having been drawn forth by a sense consciousness, are indirectly dependent on the physical sense faculties. Likewise, according to Buddhist philosophical views, many specific worldly environments have a karmic relationship with the beings living in them. In particular, the texts of the highest yoga tantra present the essential nature of the inner wind and of the mind to be that of indivisibility; thus, even in the case of a subtle mental consciousness, it is understood to be inseparable from its medium, which is the wind. Therefore, one must accept that form and consciousness are always inseparable. Nevertheless, it is not necessarily the case that inasmuch as there is consciousness, it must be contingent on the physical sense faculties as well as states of the brain.
For more about Science and Philosophy in the Indian Buddhist Classics, Volume 2: The Mind, and how the series has come together, see Michael Sheehy’s review.