 Even though the "Yongle Dadian" is itself largely lost, the remnants still contain 385 complete books that have been otherwise lost.The "leishu" also provide a unique view of the transmission of knowledge and education, and an easy way to locate traditional materials on any given subject.Approximately 600 "leishu" were compiled, from the Cao Wei period (early third century) until the 18th century, of which 200 have survived.