A poem expresses aspirations in one’s heart. Zhi (志) here means the author’s aspirations, emotions, and thoughts. The concept of “poetry expressing aspirations,” first seen in the Confucian classic The Book of History, was hailed by Zhu Ziqing as the “manifesto” of Chinese poetry. Enriched by poetry critics through the generations, it was later established as a basic concept in Chinese literary criticism.

Poems express aspirations deep in one’s heart, whereas songs are verses for chanting. (The Book of History)

Poetry is an expression of a person’s feelings and aspirations. When hidden in his heart, it is just his feelings and aspirations. When put forth through the medium of words, it becomes what is known as poetry.

(Introductions to Mao’s Version of The Book of Songs)