Unlike the future
, the recent past
is literally and figuratively an open book
to us - we see it with the clarity of having seen its consequences
as well, and 20/20 is simply another way of expressing that clarity. It is a measure of what is considered normal eyesight
. If you have 20/40 vision
, you have to stand 20 feet from a sign
to read it, while a normal person could stand at 40 feet and read it.
In some writings of fantasy
, there are beings that see the future
with clarity, but have no memories
of the past - once an event has happened, they have no knowledge
of it (see foregoblin
). Foresight is 20/20.