An excellent article on Japanese Koryu (ancient martial arts traditions that existed before the Meiji era) and the way information is taught and sometimes kept hidden. This happens a lot in the Bujinkan and is why some people criticize our art, not understanding this happens in abundance and often what is criticized are the teachers who demonstrate techniques they themselves do not understand.
https://classicbudoka.wordpress.com/2013/02/22/84-damasare-hidden-in-plain-sight/
