I believe he is saying you think you know but there's still the unknown of what you might or think you know of the unknowns. The unknown is still out there waiting to be known
The things that we all know is common knowledge. The things that we are knowing is something that can either help build or destroy this world. The things that we don't know are the ones that should never be known. They say there's no such thing as knowing too much, but if you know too much, you are a known target..... Wait....