Practicing self-cultivation, as I see it, should be made a process characterized by a “dual subtraction”. What need to undergo the “dual subtraction” in the course of self-cultivation include <1> the deluded thoughts in a practitioner’s mind, and <2> his delusion-induced activities. The dual subtraction should keep going on until the minuend is nought. The moment the minuend disappears, the practitioner’s psyche becomes perfect and ready for Buddha-nature hiding therein to surface and prick his awareness.
One of the guiding principles for a practitioner to adhere to in his course of self-cultivation dictates that he should adamantly stick to the “dual subtraction” policy, because it epitomizes Chan-based self-cultivation. Dual subtraction is in fact an aspect—and a prominent aspect—of Chan-based self-cultivation. One point needs to be made clear here is that to fulfill dual subtraction does not at all require a practitioner to spend the best part of his time practicing seated meditation every day. Rather, what is more fervently expected of a practitioner pursuing self-cultivation is his active commitment both to honestly eradicate from his psyche all the negative attachments to mundanities in his everyday life and to sincerely see through all sorts of defilements in order to discover the obscured emptiness, to detect traces of anitya (impermanence), tattvasya-laksanam (the true form of all things as they are), and alaksana (that which is devoid of marks, characteristics, and attributes). However, just as has already been cited above, “whoever turns to me for help while he is struggling for seizing some gains or whoever turns to me for beseeching me to bestow on him some propitious remarks, should be deemed as one deliberately lending himself to knavery. In that case it is absolutely out of the question that he should be favored with an insight into the origin of the manifestation of all aspects of existence.” To tell the truth, the expression, “Thus-Come” (Tathagata), refers neither to the rupa-kaya (the physical body as is manifested in the mundane world) nor to the real outward appearance of Sakyamuni. What the expression refers to is “all aspects of existence in the mundane world—an existence which looks now phantasmagorical, fizzy, and transient and then trickily fickle”. To come to the realization that there is no reality but is overpowered by transiency is the beginning of a practitioner’s embarkation on self-liberation.(From My Heart My Buddha)