Terrific fascinating shot! The hand that knocks on the door, but first you have to move it with your own hand:). Makes me think of the automatic nail hammerer: You hang it on a nail on the wall and then it hammers automatically a nail into the wall. But first you have to hammer a nail into the wall to hang it on the wall :)!
I like the texture of centuries on the hand! How many times did its knocks sound on the door?