here is the difference. it might take a few minutes to register, so read it more than once, if you have to.
when a man knows something, upon close reflection he knows that he knows.
a dog may know something. but a dog will never know that it knows.
a dog may know, but it can never know that it knows.
a man may know and can know that he knows.
think of a language that you cannot speak. let's assume it's german.
so, let's say you do not know how to speak german.
you don't know german. but you know that you don't know german.
now, let's reverse this to a positive statement.
let's say you drive a 