In The Book of Songs, the content is divided into three categories according to style and tune: feng (ballad), ya (court hymn), and song (eulogy). Ballads are music from different regions, mostly folk songs. Court hymns, divided into daya (major hymn) and xiaoya (minor hymn), are songs sung at court banquets or grand ceremonies. They are mostly the works by lettered noblemen. Eulogies are ritual or sacrificial dance music and songs, most of which praise the achievements of ancestors. Court hymns and eulogies are highbrow songs while ballads are lowbrow ones. Therefore, ballads, court hymns, and eulogies not only refer to the styles of The Book of Songs but also indicate highbrow songs. Later on fengya (风雅) generally referred to anything elegant.

Therefore The Book of Songs has six basic elements: ballads, narratives, analogies, associations, court hymns, and eulogies.

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

The three “longitudes” of The Book of Songs refer to narrative, analogy, and association, which serve as the frame of a poem. Without these, they could not be called poems. If narrative is not used in a poem, analogy must be used; if analogy is not used, association must be employed. Ballads from the states, court hymns, and eulogies play a connecting role in the poems. Since the poems have narrative, analogy, and association serving as the “longitudes,” ballads from the states, court hymns, and eulogies are therefore called the three “latitudes.” (Categorized Conversations of Master Zhu Xi)