a question of short-term memory elves

There's something that I don't
understand, if your long-term memory
is great. Which it is! You say
- and I'll witness to that,

But you're bad
at short-term memory.
So you claim? And it's not my place
to dispute! But how
does a short-term
memory, once
let slip,
return to the fold? to complete

the great and the vivid truth
in the unbroken record
your long-term keepsake
picture box

has come to hold?

What little elves
slip those gifts in,

so you open it up
and gaze on them?

They only stole them away
for a spell, perhaps
that they cast -
and it served them well, but
in token of mischief
or gratitude, they steal
to your chest,
and slip them in

just behind your heart
Where every piece nests
in its final place,

fit
snug

with the others
you can't replace.