The canon is seen partly as Emperor Yongle's way of declaring the legitimacy of his reign because he was controversial as a usurper. [Photo provided to China Daily]

For all the conjecture that surrounds the fate of the missing canon, as time goes on the chances that it will ever be found seem to diminish. However, Emperor Jiajing's devotion to the transcript gives clues to one of the major theories.

The emperor was buried three months after he died. In a month, his successor announced the transcript was completed, and it seems that from then the original disappeared without trace.

Four years before Emperor Jiajing died he urged a courtier to speed up the transcript and is said to have emphasized that the two versions would be kept in separate places.

So Luan Guiming, a researcher at the Chinese Academy of Social Sciences in Beijing and Zhang Chenshi, former editor of Zhonghua Book Company, have speculated that the canon was buried with the emperor in the Yongling tomb in northwestern Beijing.