The investigation has been going on for months, and we're still 'none the wiser' about the true cause of the accident. [=we still don't know anything more about the true cause]
I borrowed his car and returned it, and he was 'none the wiser'. [=he did not know that I had borrowed his car]
We left early, and 'no one was any the wiser'. [=no one noticed that we had left]