Undisciplined Squads of Emotion, Disciplined

Great Shun said: "Poetry is the expression of sentiments, and songs are these expressions set to music." Of this explanation, given by the sage, the meaning is clear. That which is the sentiment within the mind becomes poetry when expressed in words. It is here indeed that literary form unfurls itself to communicate reality. Poetry means discipline, disciplined human emotion. The single idea that runs through the three hundred poems in the Book of Poetry is freedom from undisciplined thought. The interpretation of poetry as disciplined human emotions is in thorough agreement with this observation.

—Liu Hsieh, The Literary Mind and the Carving of Dragons, Chapter 6 (translated by Vincent Yu-chung Shih)