The Curtain

For darkness to exist,
I must keep out the light.
Helping to hide what is there,
so that it will stay out of sight.
Once a ray is allowed in,
the darkness must scurry back.
For the illusion is broken,
and the wall begins to crack.

My barrier is thin,
some things I can't resist.
I am the border that determines,
what reality in we exist.
The questions are puzzling,
and nothing is certain.
So my life does continue,
that of a curtain.