"You don't know what you don't know"
i.e. there could be things that I should learn about, but I don't know they exist. We then decided that my training needs were "known unknowns" which led to a discussion about that famous mad quote by Donald Rumsfeld:
"There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know."
Got it? I am not sure we came to any conclusion other than I need to do some investigations.