"What is pure Mind? The Master says: “I am speaking to you, and you are listening to me. The capability to listen without discriminating, without the intervention of interpretation or judgment, is a capability of pure Mind.”
If the Mind is judgmental and discriminating, then it can no longer be called pure Mind. It is the Mind of the ordinary person because it is controlled by attachments. Take for example the phenomenon of hearing. Some can hear sound and some cannot. The deaf are aware that they do not hear sound. This knowing is an immutable characteristic of Mind. The ability to be aware of the absence of sound in the deaf is no different from the ability to be aware of the presence of sound in normal people. This ability is inherent in all human beings. Adults as well as children have it. This Mind is formless, non-discriminative and it has neither beginning nor end. It can neither be created nor annihilated. All possess the same Mind, yet, due to distortion, the oneness of Reality fragments into duality. Therefore, different things are heard. This means that even though the same words are heard, the discriminating Mind interprets the words differently. Therefore, each one forms different notions and concepts based upon these very same words because of conditioning to a certain way of thinking. What is manifested by pure Mind (Truth) is compared to what has been altered by personal judgment or interpretation (subjective reality)."
(Jian Liao: Chan)
"If the Buddha-Nature is seen, there will be no seeing of a nature in any thing."
(Nirvana Sutra, T12n374p521b3; tr. Yamamoto)
"Neither cultivation nor seated meditation — this is the pure Chan of Tathagata."
(Mazu Daoyi, X1321p3b23; tr. Jinhua Jia)
"With sudden enlightenment to Tathagata Chan,
The six paramitas and myriad means are complete within that essence."
(Yongjia Xuanjue, T2014p395c14; tr. from "The Sword of Wisdom")