A poem is like a cloud.  No two are the same.  Where one is big
and bold, another is fluff from a cotton ball or a bit of feather
from the wing of a dove.  Where another is onyx or cave gray
with purple overtones, another is ice blue or whipped cream.
Some move so slow, they fool us into thinking they are still;
some scud across the sky as if they are being chased. 

A poem is like a shell.  Again, no two are the same.  Color ranges
from black through white to incandescent.  There are shells tinged
with rose or peach or apricot, or all three;  there are shells
with mind-blowing patterns, and there are shells so unmarked,
they make you think of the foam on the waves that washed them
to shore.  If angels made porcelain, it would look like them.
Some are tougher than nails, others are fragile as spun glass.
Most have secrets you can’t get at.  Most come from someplace
very deep.  All create subtle changes in us if we really look.
Hold one to our ear and listen without judgement.

A poem is none of the above, and so much more. 
                                                                                          A mystery!