I thought i heard you knocking

I thought I heard you knocking
As I sprung up from my chair
Flung the door wide open
There was no one standing there
It's getting harder every moment
To tell what's really real
Sometimes it ain't the things you know
It's more the way you feel
I thought I heard you knocking
Tapping soft and light
Like the sounds an old house offers
When it settles for the night
You used to be just as familiar
Like whiskey on my breath
Now whenever you come calling
You scare me half to death
Haven't you already had your fun
Or maybe this has only just begun
You got me wondering should I stay or should run
Won't you tell me what you think it is I done
I thought I heard you knocking
Like a hard rain tumbling down
When I strain my ears to listen
I can scarcely hear the sound
Some questions they have answers
And you never ask again
Some questions only lead
To places you've already been
It's such a dark and bitter seed you've sown
I've got a worried feeling deep down in my bones
If I look at you will I just turn to stone
I don't know why you won't leave me alone
I thought I heard you knocking
Sharp and shallow on my door