Attacking it logically it means that things are...
a) not what they appear to be...
nor are they...
b) what they do not appear to be.
so, seeing as how that covers every possible alternative, that means that things are not anything.
Not exactly profound, but I think it sounds kind of cool. It sounds like it could be a quote from Alice in Wonderland.
Yesterday, upon the stair,
I met a man who wasn't there.
He wasn't there again today,
I wish, I wish he'd go away.