Tao stood firmly and steadied the board with both hands. Ahe eased it back into line with its neighbors. Little by little, the wide gap closed.

“Keep holding it,” he said. He moved the upper rope to the place where board and rail crossed, tightened it, and tied it firmly. Then he secured the lower rope. Only when both were fastened did he nod.

Tao slowly let go. The board stayed upright. Ahe gave it a gentle push; it no longer wobbled. “Putting it in place isn't enough. We have to keep it there.” Tao touched the firm knot and smiled.