Zhang Dao Ling, or Zhang Celestial Master,  was an Eastern Han Dynasty (2nd Century CE) Taoist hermit who was the co-founder of Taoism.  It is said that Zhang Celestial Master possessed the ability to chase away the demons,  expel the evil and then cure the sick.  Since then, many people did not go to see a doctor when they were ill, instead they called a Taoist priest who would read off the chants that were on the tallies, and the symptoms would abate.  (7/20/2010)