The poem
Stairs fly as straight as hawks; Or else in spirals, curve out of curve, pausing At a ledge to poise their wings before relaunching. Stairs sway at the height of their flight Like a melody in Tristan; Or swoop to the ground with glad spread of their feathers Before they close them.
They curiously investigate The shells of buildings, A hollow core, Shell in a shell.
Useless to produce their path to infinity Or turn it to a moral symbol, For their flight is ambiguous, upwards or downwards as you please; Their fountain is frozen, Their concertina is silent.