I thought I knew nothing about ninjas, since I had never actually studied ninjas, only got information from movies and manga, then I heard a historian supposedl

I thought I knew nothing about ninjas, since I had never actually studied ninjas, only got information from movies and manga, then I heard a historian supposedly specialized in ninjas give a talk titled "Everything you know about ninjas is wrong" or somewhat like that. 90% of what he has said met what I already knew and believed (even though I wasn't very sure of what I knew).