A term widely used in pop circles of Buddhism and Zen is duality. I hope to shed a little more light on it. One could say that duality or dvaya (two-fold, double, of two kinds or sorts) is at the heart of vijñāna (often translated by 'consciousness') which really means, in two-parts knowing since the prefix vi- can mean “in two parts” whereas jñāna just means “knowing.” This would apply, for example, to subject and object knowing, observer and observed knowing, and so on. What did the Buddha say about consciousness?
Whatever suffering arises in the world, all is caused by consciousness. With the cessation of consciousness, there is no arising of suffering. Knowing this danger, that suffering is caused by consciousness, with the stilling of consciousness, one is wishless, quenched (Sutta Nipata, Dvayatānupassanā sutta).
The Buddha also said:
At Sāvatthī. Mendicants, what you intend or plan, and what you have underlying tendencies for become a support for the continuation of consciousness. When this support exists, consciousness becomes established (SN 12:38).
The cessation of consciousness is really the cessation of dvaya which reveals advaya this being ultimate reality. This would also be the One Mind or Mind-only in which the dualizing nature of consciousness has not come forth to dominate.
When in Zen we attain kenshō we have transcended duality and with it consciousness. This is the stilling of consciousness. But more importantly, we have put an end to transmigration because it is consciousness which is the transmigrant. This is something very seldom touched upon. Pop Buddhists believe there is no transmigrant since the Buddha denied the Ātman. They are wrong on both counts.