Yingzao Fashi
If it were not for Shen Kuo's analysis and quoting in his "Dream Pool Essays" of the writings of the architect Yu Hao (fl. 970), the latter's work would have been lost to history. Yu designed a famous wooden pagoda that burned down in 1044 and was replaced in 1049 by a brick pagoda (the 'Iron Pagoda') of similar height, but not of his design. From Shen's quotation—or perhaps Shen's own paraphrasing of Yu Hao's "Timberwork Manual" (木經; "Mujing")—shows that already in the 10th century there was a graded system of building unit proportions, a system which Shen states had become more precise in his time but stating no one could possibly reproduce such a sound work. However, he did not anticipate the more complex and matured system of unit proportions embodied in the extensive written work by scholar-official Li Jie (1065–1110), the "Treatise on Architectural Methods" (營造法式; "Yingzao Fashi") of 1103. Klaas Ruitenbeek states that the version of the "Timberwork Manual" quoted by Shen is most likely Shen's summarization of Yu's work or a corrupted passage of the original by Yu Hao, as Shen writes: "According to some, the work was written by Yu Hao."