Beyond the literal 'ten days',
十日 carries strong mythological weight: in the legend of
后羿射日 (Hòu Yì shè rì, 'Hou Yi shoots the suns'), ten suns once rose together and scorched the earth, and the archer Hou Yi shot down nine to save the world. The phrase also names Boccaccio's 《
十日谈》 (Shírì Tán, The Decameron) in Chinese.