What is reality? Dictionaries tell us that reality is "the state of things as they actually exist." In Mahayana Buddhism, reality is explained in the doctrine of the Two Truths.
This doctrine tells us that existence can be understood as both ultimate and conventional (or, absolute and relative). Conventional truth is how we usually see the world, a place full of diverse and distinctive things and beings. The ultimate truth is that there are no distinctive things or beings.
To say there are no distinctive things or beings is not to say that nothing exists; it is saying that there are no distinctions. The absolute is the dharmakaya, the unity of all things and beings, unmanifested. The late Chogyam Trungpa called the dharmakaya "the basis of the original unbornness."
Confused? You are not alone. It's not an easy teaching to "get," but it's critical to understanding Mahayana Buddhism. What follows is a very basic introduction to the Two Truths.
Nagarjuna and Madhyamika
In the Kaccayanagotta Sutta (Samyutta Nikaya 12.15) the Buddha said,
"By and large, Kaccayana, this world is supported by (takes as its object) a polarity, that of existence and non-existence. But when one sees the origination of the world as it actually is with right discernment, 'non-existence' with reference to the world does not occur to one. When one sees the cessation of the world as it actually is with right discernment, 'existence' with reference to the world does not occur to one."
The Buddha also taught that all phenomena manifest because of conditions created by other phenomena (dependent origination). But what are the nature of these conditioned phenomena?
An early school of Buddhism, Mahasanghika, had developed a doctrine called sunyata, which proposed that all phenomena are empty of self-essence. Nagarjuna developed sunyata further. He saw existence as a field of ever-changing conditions that cause myriad phenomena. But the myriad phenomena are empty of self-essence and take identity only in relation to other phenomena.
Echoing the words of the Buddha in the Kaccayanagotta Sutta, Nagarjuna said that one cannot truthfully say that phenomena either exist or don't exist. Madhyamika means "the middle way," and it is a middle way between negation and affirmation.
The Two Truths
Now we get to the Two Truths. Looking around us, we see distinctive phenomena. As I write this I see a cat sleeping on a chair, for example. In conventional view, the cat and the chair are two distinctive and separate phenomena.
Further, the two phenomena have many component parts. The chair is made of fabric and "stuffing" and a frame. It has a back and arms and a seat. Lily the cat has fur and limbs and whiskers and organs. These parts can be further reduced to atoms. I understand that atoms can be further reduced somehow, but I'll let the physicists sort that out.
Notice the way the English language causes us to speak of the chair and of Lily as if their component parts are attributes belonging to a self-nature. We say the chair has this and Lily has that. But the doctrine of sunyata says that these component parts are empty of self-nature; they are a temporary confluence of conditions. There is no-thing that possesses the fur or the fabric.
Further, the distinctive appearance of these phenomena -- the way we see and experience them -- is in large part created by our own nervous systems and sense organs. And the identities "chair" and "Lily" are my own projections. In other words, they are distinctive phenomena in my head, not in themselves. This distinction is conventional truth.
(I assume I appear as a distinctive phenomenon to Lily, or at least as some kind of complex of distinctive phenomena, and perhaps she projects some kind of identity onto me. At least, she doesn't seem to confuse me with the refrigerator.)
But in the absolute there are no distinctions. The absolute is described with words like boundless, pure, and perfect. And this boundless, pure perfection is as true of our existence as fabric, fur, skin, scales, feathers, or whatever the case may be.
Also the relative or conventional reality is made up of things that can be reduced to smaller things down to atomic and sub-atomic levels. Composites of composites of composites. But the absolute is not a composite.
In the Heart Sutra, we read, "Form is no other than emptiness; emptiness no other than form. Form is exactly emptiness; emptiness exactly form." The absolute is the relative, the relative is the absolute. Together, they make up reality.
A couple of common ways that people misunderstand the Two Truths --
One, people sometimes create a true-false dichotomy and think that the absolute is true reality and the conventional is false reality. But remember, these are the two truths, not the one truth and one lie. Both truths are true.
Two, absolute and relative are often described as different levels of reality, but that may not be the best way to describe it. Absolute and relative are not separate; nor is one higher or lower than the other. This is a nitpicky semantic point, perhaps, but I think the word level could create a misunderstanding.
Another common misunderstanding is that "enlightenment" means one has shed conventional reality and perceives only the absolute. But the sages tell us that enlightenment actually is going beyond both. The Chan patriarch Seng-ts'an (d. 606 CE) wrote in the Xinxin Ming (Hsin Hsin Ming):
At the moment of profound insight,
you transcend both appearance and emptiness.
And the 3rd Karmapa wrote in the Wishing Prayer for the Attainment of the Ultimate Mahamudra ,
May we receive the flawless teachings, the foundation of which are the two truths
Which are free from the extremes of eternalism and nihilism,
And through the supreme path of the two accumulations, free from the extremes of negation and affirmation,
May we obtain the fruit which is free from the extremes of either,
Dwelling in the conditioned state or in the state of only peace.