Just speak normally - Star Trek: Website

my parents always say it’s “quarter of”. I can’t make it make sense.
I knew a mathy type who would occasionally jokingly say “a third past”
I think Kafka used stuff like “two and a third” sometimes

Right?!

Quarter til, quarter after…those are easy to understand. Same goes for half past.

But quarter of? I have no idea how that relates to the passage of time.