The Feilin City's library was unlikely to have some groundbreaking knowledge about Medicine Dao and Wood attribute that Wu Long was not aware of.
However, it had a lot of research made by scholars and practitioners of the Medicine Dao who lived here in the past, each making their own very specific small research and recording their findings.
Knowledge that was only local to this continent and was not really valuable enough to be spread widely beyond it.
And as Wu Long never visited this continent before, it naturally was something that he never saw.
Sometimes, such seemingly insignificant and specific information could inspire a larger realization or enlightenment, or lead to some breakthrough in a completely unrelated and unexpected different field of knowledge.
