My friend Sean is a kind of concaveman
He builds, with the minimum of tools, better than anyone can.
He scribes a wall that's not just curved inside,
but has concaved vertical batter right up its sides.
It goes gently in, and then steps gently out.
He goes up and over, and has no doubt
He surrounds himself with concavity
Gradually, defying gravity.
The wall wraps round him in concentric courses .
Holding back all nature's forces,
From caving in his womb of stone,
Within the sphere of the unknown.
