Another legend states that Emperor Xuanzong sent Wu Daozi to Sichuan to study the green waters of the Jialing River in order to complete a mural of its entire course. Supposedly, Wu returned without sketches and rapidly painted the entire river from memory, completing the 300-li account within a single day. It is sometimes added that his technique was foiled by Li Sixun, who accompanied him and followed the traditional practice of working slowly from numerous prepared sketches. To the extent that it is grounded in a real event, however, it probably only reflects Wu's speed of execution and not a lack of reliance on sketches.