Isn't that nostrum irritating about how the wise person is the one who knows how much he doesn't know? I mean, if he really knows he doesn't know, then he knows. Quit disavowing you know anything. It's false modesty. You do know something. You know what you know, and what you don't know, you don't know. You don't know that you don't know. Otherwise, you know.
Now maybe you define some of your knowledge in terms of what you don't know. That's still knowledge! You see all the stars and planets but you don't know their names, perhaps. So you say, there's a galaxy out there but I am only vaguely aware of its vast complexities. That is my infinitesimal piece of knowledge and that will satisfy. Not! Who are you kidding? In my book, you aren't satisfied with half a glass. Only the whole draught will quench the thirst. And when you quaff it to the lees, you know that you have drunk. You know that you are experienced, as Jimi Hendrix says.
He who is wise, knows what he knows and doesn't know what he doesn't know. That is the truth.