It is the only place to be alone in such a crowd. He feels like a bird, above the ground, resting on nothing but air. He is not of this place but above it, apart from it, observing it. It brings to mind, for him, the wind-hovering kestrel his wife used to keep, and the way it would hold itself in high currents, far above the tree tops, wings outstretched, looking down on all around it.
