At the Mid-Autumn Festival of 1076, in Mizhou, Su Shi wrote the poem that begins: “How long has the bright moon been there? I raise my cup and ask the blue sky.” Its title, Shuidiao getou, does not describe the poem. It names a fixed pattern.
A cipai, or tune pattern, became a fixed form for the wording and the rhymes. Shuidiao getou has 95 characters in two stanzas, with four level-tone rhymes in each. Mi Fu, Huang Tingjian and Zhang Yuangan also wrote poems to this pattern, each with new words.
The pattern was itself made from an older part. Song poets took the opening section of a longer Tang suite called Shuidiao.