Much of the text works on preventing errors in the conceptualization of mind. Mind cannot, by definition, be an object of experience; it is not something to which a practitioner of Zen could come into relation. Mind is also not something within the totality of things, since it is the formless background against which all things can be experienced. The Huang-po texts are skillful in insisting that this mental background is essentially “open” or “empty”; every effort to put yourself before it excludes you from it. Nor is mind the subject of experience. Therefore the texts claim that in “mind” there is “no subject, no object, no self, no other.”30 Mind and objects of mind “co-arise” and are therefore undifferentiated. Since, as P'ei-hsiu writes, Huang-po taught nothing but “mind,” we will have occasion in explaining the ideas that follow to say more about this elusive Zen symbol.
4. The Concept of Sudden Awakening
The idea that awakening entails a sudden breakthrough into a mode of consciousness that has always been fundamental to your being but never truly seen is basic to the Huang-po literature. Reference to it appears numerous times in the text, even though little time is spent dwelling on the idea. Conscious reflection on this theme would not have been necessary in Chinese Buddhism of the ninth century because the mainstream of the tradition had several centuries before this period to come to a consensus—enlightenment is a sudden, unexpected, unplanned, and incomprehensible event that befalls the practitioner even though he or she may have spent an entire career striving to attain it.
The only question that remained was how exactly to account for it, or how to connect it to Buddhist practice and to the other concepts of the tradition. This is where Huang-po was innovative, and rhetorically powerful. In working with sudden awakening, Huang-po and the Hung-chou tradition of Zen took up the Taoist theme that since you already reside within the Way, and cannot escape it, there is “nothing to do.” Enlightenment, therefore, is simply awakening to this fact. Therefore, the text says, “Awakening suddenly, you realize that your mind is the Buddha, that there is nothing to be attained, nor any act to be performed. This is the true way, the way of the Buddha.”34
There were a number of cultural and spiritual forces behind the emergence of the Chinese doctrine of sudden awakening, but an important one was the philosophical realization that it did not make sense to claim that something truly transcendent emerged out of the world in incremental stages, as if enlightenment were just more of the many phenomena things found in the world of unenlightenment. Ideas about “stages of practice,” therefore, which were vital to early T'ang-dynasty Buddhist thought, came under heavy critique in the Zen tradition. Thus, the Huang-po texts explain how “the six perfections and other similar practices, which seek buddhahood through advancement along stages,”35 are simply misguided; they fail to understand what kind of a realization buddhahood might be. “The real Buddha is not a Buddha of stages!”36
http://www.thezensite.com/ZenEssays/His ... ature.html