In my understanding, ' as we know it ' usually follows a noun phrase and means like the building as we know it = the version/condition of. It would only have that sense if you added. Recently one of my friends told me that there is distinct difference between 'know of something' and 'know about something' expressions.
Bright moon followed by sunny skies light up the Big Bend and South
This sentence is from the commentary of planet earth. Earth is the only planet we know of where life exists. Why do you think that he doesn't know him from his schooldays means that he does know him?
Why it is know of in.
It's like when saying did you know strawberries aren't berries, but bananas are?, i didn't know if. Because you've just told them!
