I sit at my desk, perched on my chair. Out the window, a robin patrols the roof, protecting her nearby nest.
Whose house is this?
To her, I am invisible — the interior of the house does not exist. When I emerge from the front door, she cannot fathom my world, but she swoops and screeches, protecting her children from this seeming intruder. I exit my world and enter hers.
She knows this house as well as I do. The slope of the roof, the places that give shade. It is hers because of this knowledge, because of her presence.
There are, in fact, two houses.
Perhaps there is no house — simple two (infinite?) stories anchored to this particular play of shadow and light.