Vast emptiness, no merit
Bodhidharma's reputation as a Dhyana master was said to have preceded his arrival in China, and so and the Chinese Emperor Wu, a devout Buddhist, called upon Bodhidharma to visit the Imperial Palace to teach. Having sponsored the construction of a great many Buddhist monasteries and temples and patronizing the teachers of the various Buddhist sects, Emperor Wu—in accordance with his understanding of their teachings—assumed that he would gain much 'merit' in the form of a happy and prosperous reign. And he assumed he was earning an auspicious rebirth in what some Buddhist schools called a 'Pure Land' where, unlike on earth, all the conditions of life would be conducive to his attainment of Enlightenment.
Emperor Wu: "I have built many temples, copied innumerable Sutras and ordained many monks since becoming Emperor. Therefore, I ask you, what is my merit?"
Bodhidharma: "None whatsoever!" answered Bodhidharma.
Emperor Wu: "Why no merit?"
Bodhidharma:: "Doing things for merit has an impure motive and will only bare the puny fruit of rebirth."
Emperor Wu, a little put out: "What then is the most important principle of Buddhism?"
Bodhidharma: "Vast emptiness. Nothing sacred."
Emperor Wu, by now bewildered, and not a little indignant: "Who is this that stands before me?"
Bodhidharma: "I do not know."
This legendary interchange, with Bodhidharma's inspiring directness and unsparing responses, became for later generations of Chan practitioners a model for telling things as they are, without pulling any punches.
No merit, Bodhidharma told the astounded emperor! No merit, no lack of merit. No giver of merit, no receiver. Although the emperor likely misunderstood the teaching as a rebuke, Bodhidharma was pointing to the true merit that derives from seeing one's own true nature, one's Buddha nature.
"Vast emptiness, nothing sacred." Right from "the beginning" we see Zen's spare uncompromising tone. And, as Peter Mathiessen points out, great mystery and power.
This "emptiness" was neither absence nor a void. . . Like the empty mirror on which all things pass, leaving no trace, this ku contains all forms and all phenomena, being a symbol of the universal emphasis. Thus this emptiness is also fullness, containing all forms and phenomena.
"I do not know."
And with "I do not know." Bodhidharma launches Zen with the supreme answer. As Peter Mathiessen observes, not-knowing:
. . . echoes "vast emptiness," yet goes still deeper to the unnameable source where there is noting-to-know, were nothing exists outside the doing and being of this present instant witout past and future. . . . Like emptiness, this not-knowing is very close to us, therefore hard to see. It is the source or essence of our life, and of Zen practice. .
This "not-knowing" links Bodhidharma directly to the existing Taoist notion of wu-nien (no thought) and is an early example of Buddho-Taoist vocabulary.