Zuo Si (Chinese characters: 左思; Hanyu Pinyin: Zuǒ Sī) (250–305), courtesy name Taichong (太沖), was a writer and poet of the Western Jin.
Zuo was born to an aristocratic family of Confucian scholars in Linzi. His mother died young. His father, Zuo Yong, was promoted to imperial official in charge of the imperial archives. Zuo Si would often play word games with his sister, Zuo Fen, who later became famous in her own right as a writer and a concubine of Emperor Wu of Jin.
In approximately 280, Zuo wrote the "Shu Capital Rhapsody" (蜀都赋), the first of his rhapsodies on the three capitals of the Three Kingdoms Period. The Shu Capital Rhapsody described the city of Chengdu and the surrounding area. This work features the earliest surviving reference to Mount Emei. The work was so highly renowned and frequently copied upon its release that the price of paper in Luoyang is said to have risen as a result. This later gave rise to the popular Chinese idiom 洛阳纸贵 ("Paper is Expensive in Luoyang"), today used to praise a literary work.
Zuo described his rhapsodies on the three capitals as derivative of similar works by Zhang Heng and Ban Gu. However, Mark Edward Lewis has written that Zuo's rhapsodies marked the end of the Han Dynasty ideal of the ritually perfect capital, because they describe three simultaneously existing, contemporary capitals, suppressing the ritual and historical evolution that structured the previous works. Zuo argued for accuracy as the basis of poetry, in contrast to the fantastic writings of Han poets. In his preface to the three rhapsodies, he wrote that while writers of lyric verse "sing of what their hearts are set upon", writers of descriptive rhapsodies "praise what they observe".