In the practice of Zen, the truth is not contained within the form; it is the transcendence of consciousness toward the experience of the ineffable that matters.
In Christianity we refer to this very same ineffable reality as the "apophatic tradition." It is a reference to the transcendent nature of the divine reality that is God, an infinite reality that cannot be understood, or expressed from the perspective of a finite being.
In the Christian tradition, Christian contemplatives developed a mode of expressing God’s nature known as the via negative, the negative way. The understanding being that we can never adequately state, or positively affirm what is true about the infinite nature of God. We can only state what God is not.
We cannot even say that God is love, that God is good, or that God is just, because our understanding of love, and goodness, and justice is necessarily circumscribed and limited by our position in the universe as finite beings, conditioned by both time and space.
We can only say that God is not hate, God is not evil, and God is not corrupt.
The very same idea is similarly represented in the Hebrew use of the tetragrammaton YHWH for the name of the deity, the God of Abraham, Isaac and Jacob. In the Hebrew tradition the name of the deity cannot even be expressed, let alone represent as a graven image. The tetragrammaton stands in the place God’s name, representing the deity, the fundamental reality that is the source of all being.
The sutras at best point in the direction of the truth. But because the truth is ultimately inexpressible any attempt to contain it within a sentence, an essay, or a poem, must ultimately meet with failure.
The primary sutras in the Zen cannon are the Prajnaparamita, sutras (the sutra on emptiness), and the Platform sutras of the sixth Patriarch.
The sutra on emptiness stresses the goal of za-zen: to release the mind from its attachment to things. "The Platform sutra warns against false practice, especially against clinging to purity or emptiness."[i] The emphasis that Hui-neng, the sixth Patriarch places on the non-attachment of the mind to the concept of emptiness is indicative of how it is that the mind will try to objectify any concept.
It is the process of objectifying reality that causes our view of it to become, and remain circumscribed. The circumscribed mind is focused of finitudes, and thus is unable to experience the infinite. In turn, this keeps the experience of enlightenment out of the hand of the practitioner who is reaching for it.
As a means of preventing the practitioner of Zen from a meaningless objectification of his or her studies, the koan method was developed.
The koan is a verbal puzzle which usually boils down to an a-rational concept or paradox.
Meditating on a koan is meant to afford the practitioner the opportunity to shock his or her mind out of the mundane, and into the super-reality of the Buddha mind.
"The koan exercises which are the prevailing method at present of mastering Zen involves many years of close application."[ii] D. T. Suzuki tells us.
All things are reducible to the One, and where is this One reducible? Keep this koan in your mind and never allow yourself to think that quietude or a state of unconsciousness is the sine qua non in your koan exercise. When you feel confused in your mind so that your power of attention refuses to work its own way, do not try to gather it up with a thought, but mustering your spirits keep up your koan by all means before you. Courage and determination are most in need of at this juncture.[iii]