Literary flexibility means that one should respect the rules for writing poetry or prose but not be bound by them; one should encourage change and innovation. The opposite of literary flexibility is literary rigidity under whose influence the writer mechanically imitates the forms of established writers without innovation. One way to attain literary flexibility in one’s works is to draw inspiration from others extensively and absorb their talent while refraining from sticking mechanically to the model. One should base oneself on his own feelings and the aesthetic principles so as to create new styles and new ways of expression. Influenced by the Chan spirit of liberal flexibility, literary critics of the Song Dynasty championed flexibility in literary pursuit and established it as an important principle guiding poetry and prose writing.
- 学诗当识活法。所谓活法者，规矩备具，而能出于规矩之外，变化不测，而亦不背于规矩也。是道也，盖有定法而无定法，无定法而有定法。知是者则可以与语活法矣。 （刘克庄《后村集》卷二十四引吕本中《〈夏均父集〉序》） （学作诗要懂得活法。所谓活法，就是作诗的各种规矩法度全都具备，又能跳出规矩法度的限制，使诗文产生各种不可预测的变化，而且还不违背规矩。这个道理就是，说有恒定的规矩法度又没有恒定的规矩法度，说没有恒定的规矩法度却又有恒定的规矩法度。懂得这个道理的人，就可以与他谈论活法了。）
Those who wish to learn to write poetry should master literary flexibility. By this I mean that, while knowing all the rules for poetry, the poet goes beyond them to reflect unpredictable changes in his poetry yet without compromising the rules. The principle underlying this way of writing is that there should be set rules, yet they are not fixed; where there seem to be no rules, rules do exist. You can discuss literary flexibility with others only if they understand this principle. (Lü Benzhong: Foreword to The Collected Poetry of Xia Junfu)
- 文章一技，要自有活法。若胶古人之陈迹，而不能点化其句语，此乃谓之死法。死法专祖蹈袭，则不能生于吾言之外；活法夺胎换骨，则不能毙于吾言之内。毙吾言者，[ 故为死法；] 生吾言者，故为活法。 （俞成《萤雪丛说·文章活法》） （写文章这种技艺，必须有自己的活法。如果只是拘泥于古人的陈法，而不能将他们的词句化陈出新，这就叫死法。死法只会因袭模仿，不能让我的文章在语言之外获得新生。活法则能超凡脱俗，不会让我的文章被语言困死。文章被语言困死，[ 所以称死法；] 使文章在语言之外获得新生，所以称活法。）
In writing essays, it is necessary to maintain literary flexibility. If one is bound by the clichés of the classical masters and fails to produce novel ideas, this is what we call literary rigidity. Literary rigidity refers to mechanically copying others without permitting one’s own work to acquire new ideas. Literary flexibility, however, allows one’s work to free itself from clichés so that the work will not be stifled by stereotyped style of writing. Literary rigidity leads to a literary dead end, while literary flexibility encourages the birth of new ideas by going beyond the limitations of conventional way of writing. (Yu Cheng: Reflections from Devoted Reading)