Analysis of The Lockless Door

It went many years,
But at last came a knock,
And I thought of the door
With no lock to lock.

I blew out the light,
I tip-toed the floor,
And raised both hands
In prayer to the door.

But the knock came again
My window was wide;
I climbed on the sill
And descended outside.

Back over the sill
I bade a "Come in"
To whoever the knock
At the door may have been.

So at a knock
I emptied my cage
To hide in the world
And alter with age.