(fact: piece missing) (illusion: piece necessary)

[coffiend]

It was missing a piece.
And it was not happy.
So it set off in search
of its missing piece.

...

so on and on it rolled,
having adventures
falling into holes
and bumping into stone walls.

And then one day it came upon
another piece that seemed
to be just right.

...

"Aha," it thought.
"So that's how it is!"
So it stopped rolling...
and it set the piece down gently,
and slowly rolled away
and as it rolled it softly sang-
"Oh I'm lookin' for my missin' piece
I'm lookin' for my missin' piece
Hi-dee-ho, here I go,
Lookin' for my missin' piece."