Puzzle

Such a puzzle I have never seen.
I am all unsure,
as the pieces sit before me,
just where to begin
to arrange them;
they seem to change before my eyes
in color, shape, and size.
A familiar piece? Yes, it's there
just in front of me.
I can see where it fits;
but, with so much space to fill,
it's bound to be a while
before the puzzle is complete,
and the picture it was meant to show
takes its place.
For now, I know
this puzzle is a mystery to me.