I Am A Door

I am a door
A door that shuts by itself
A door that locks

I am a door
A door that conceals what's behind it
A door that lets nothing in - or out

I am a door
A door that is wooden and hollow
A door that echoes when you knock, but no one answers

I am a door
A door that has a peep-hole so in can look out, but out can't look in
A door that won't open....