灵枢经·逆顺 Counterflow and Compliance
黄帝问于伯高曰：余闻气有逆顺，脉有盛衰，刺有大约，可得闻乎？伯高曰：气之逆顺者，所以应天地阴阳四时五行也；脉之盛衰者，所以候血气之虚实有馀不足；刺之大约者，必明知病之可刺，与其未可刺，与其已不可刺也。
黄帝曰：候之奈何？伯高曰：兵法曰无迎逢逢之气，无击堂堂之阵。刺法曰：无刺熇熇之热，无刺漉漉之汗，无刺浑浑之脉，无刺病与脉相逆者。
黄帝曰：候其可刺奈何？伯高曰：上工，刺其未生者也；其次，刺其未盛者也；其次，刺其已衰者也。下工，刺其方袭者也；与其形之盛者也；与其病之与脉相逆者也。故曰：方其盛也，勿敢毁伤，刺其已衰，事必大昌。故曰：上工治未病，不治已病，此之谓也。
Huangdi asked Bogao, saying: 'I have heard that qi has its states of counterflow and compliance, that the pulse has its states of exuberance and decline, and that needling has its overarching principles — may I hear about these?' Bogao said: 'The counterflow and compliance of qi correspond to Heaven and Earth, yin and yang, the four seasons, and the five phases. The exuberance and decline of the pulse serve to indicate the deficiency, excess, surplus, or insufficiency of blood and qi. The overarching principle of needling is that one must clearly understand when a disease can be needled, when it cannot yet be needled, and when it can no longer be needled.'
Huangdi said: 'How does one observe this?' Bogao said: 'The art of war says: do not meet head-on an army advancing with banners flying in full array; do not strike an enemy formation arrayed in imposing order. Similarly, the art of needling says: do not needle a blazing, scorching fever; do not needle a profusely dripping sweat; do not needle a pulse that is turbulent and chaotic; do not needle when the disease and the pulse are in mutual contradiction.'
Huangdi said: 'How does one determine when a disease may be needled?' Bogao said: 'The superior physician needles a disease before it has arisen; the next best physician needles it before it has become exuberant; the next needles it after it has already begun to decline. The inferior physician needles a disease just as it is striking; needles when the body's form is at its most exuberant; and needles when the disease and the pulse are in mutual contradiction. Hence it is said: while a disease is at its height, one must not dare to attack it; needle it only once it has begun to decline, and the outcome will surely be excellent. Hence it is said: the superior physician treats illness that has not yet arisen, not illness that has already arisen — this is precisely what is meant.'