This credo is remembered most vividly in two anecdotes that were later enshrined in a famous collection of koans called the Wu-men Kuan (or Mumonkan in Japanese). In both of these anecdotes, Ma-tsu is asked, "What is Buddha?"--meaning what is the spirituality that all seek. In one he replied, "Mind is Buddha" (Mumonkan, Case 30), and in the other anecdote he said, "No mind, no Buddha" (Mumonkan, Case 33), which merely affirms that spirituality is in the mind, and for its realization one must realize the mind.13 In either instance he is merely following the earlier idea that there is no reality and thus no enlightenment outside the mind. These two exchanges are part of a single anecdote of Ma-tsu recorded in the chronicles. _A monk asked why the Master maintained, "The Mind is the Buddha." The Master answered, "Because I want to stop the crying of a baby." The monk persisted, "When the crying has stopped, what is it then?" "Not Mind, not Buddha," was the answer. "How do you teach a man who does not uphold either of these?" The Master said, "I would tell him, 'Not things.' " The monk again questioned, "If you met a man free from attachment to all things, what would you tell him?" The Master replied, "I would let him experience the Great Tao._"14_ _As the scholar John Wu has pointed out, "This dialogue reveals an important secret about Ma-tsu's art of teaching. Sometimes he used a positive formula, sometimes he used a negative formula. On the surface they are contradictory to each other. But when we remember that he was using them in answering persons of different grades of attainments and intelligence, the contradiction disappears at once in the light of a higher unity of purpose, which was in all cases to lead the questioner to transcend his present state."15 Another example of a seemingly contradictory position is recorded as a koan in another famous collection, the Blue Cliff Record (Case 3). In this anecdote, Ma-tsu is asked one day about his health, and he responded with, "Sun-faced Buddhas, Moon-faced Buddhas."16 According to a Buddhist tradition, a Sun-faced Buddha lives for eighteen hundred years, a Moon-faced Buddha lives only a day and a night. Perhaps he was proposing these two contradictory cases to demonstrate the irrelevance of an inquiry after his physical state. It would have been far better if the question had concerned his mind. A story describing how Ma-tsu handled other teachers who wandered by depicts very well the way that he could undermine logic and categorization. In a particularly famous anecdote, a visiting teacher proposed a condition of duality, a condition equivalent to that of a switch that can be either off or on. Having permitted the teacher to adopt this very un-Zen position, Ma-tsu proceeds to demolish him. The story goes as follows: