Ch'an began by working out the question of what this enlightenment really is. Prior to Ma-tsu the search was more for the nature of enlightenment than for its transmission. This was the doctrinal phase of Ch'an. As time went by, however, the concern shifted more and more from defining enlightenment--which the Ch'an masters believed had been done sufficiently--to struggling with the process. After Ma-tsu, Ch'an turned its attention to "auxiliary means" for helping along transmission: paradoxical words and actions, shouts, beatings, and eventually the koan.1 The koan, then, is the final step in the "auxiliary means." A succinct analysis of the koan technique is provided by Ruth F. Sasaki in _Zen Dust_: "Briefly, [koans] consisted of questions the early masters had asked individual students, together with the answers given by the students; questions put to the masters by students in personal talks or in the course of the masters' lectures, together with the masters' answers; statements of formulas in which the masters had pointed to the profound Principle; anecdotes from the daily life of the masters in which their attitudes or actions illustrated the functioning of the Principle; and occasionally a phrase from a sutra in which the Principle or some aspect of it was crystallized in words. By presenting a student with one or another of these koans and observing his reaction to it, the degree or depth of his realization could be judged. The koans were the criteria of attainment."2 Called _kung-an _in Chinese (meaning a "case" or a problem), the koan was a response to two major challenges that beset Ch'an in the Sung era: First, the large number of students that appeared at Ch'an monasteries as a result of the demise of other sects meant that some new means was needed to preserve personalized attention (some masters reportedly had one thousand or even two thousand followers at a monastery); and second, there was a noticeable decline in the spontaneity of both novices and masters. The masters had lost much of the creative fire of Ch'an's Golden Age, and the novices were caught up in the intellectual, literary world of the Sung, to the point that intellectualism actually threatened the vitality of the sect.