Dick Marcinko is a former Navy SEAL and an author of many books.  The most famous of them being the Rogue Warrior series of international military thriller type action novels.  But he also wrote the “Leadership Secrets of the Rogue Warrior” and “A Commando’s Principle of Winning”

It is from one of these two books that (I believe) this quote came from.  It is very worth revisiting at times.

“Conventional wisdom is no wisdom at all. Conventional wisdom is taking somebody else’s word for the way things are… It’s the followers of this world who rely on assumption. Not the leaders.”

– Richard Marcinko