The term refers to the use of allegories to convey popular mood and public opinion and make critical comments on state affairs to the ruler in a tactful manner in the hope to persuade him to correct wrong policies. Feng (讽) represents making critical but persuasive comments subtly through poetry or prose; yu (喻) means delivering an explicit message. Such literary writing is intended to be both critical and persuasive; and it has two integral aspects, namely, a subtle literary way of expression as required by feng, and its social function of sending explicit messages to the ruler as required. The theory of subtle admonition was advocated by scholars of the Han Dynasty based on their interpretation of The Book of Songs. Confucian scholars from then on promoted the use of subtle admonition to influence decision-making of the ruler and social mores in a literary way. Bai Juyi（772-846）, a poet of the Tang Dynasty, wrote many such poems, further reinforcing the social function of poetry and advancing this literary tradition, which had great impact on literary creation of later generations.

Some literary works use subtle admonition to convey what the subjects think and feel, in the hope that the subtle advice could reach the ruler, whereas other works expound the kindness and benevolence of the ruler so as to guide the populace to fulfilling their duties and obligations. (Ban Gu: Preface to “Essays on Chang’an and Luoyang”)

Writings by ancient scholars could be said that at a higher level they aimed at explaining some kind of link between the ideas of the ruling court and popular sentiment in society. At a more practical level, they sent a clear message of advice to the rulers through allegories. (Bai Juyi: Collection of Essays in Preparation for the Final Round of the Imperial Examination)