Nothing is built on stone; all is built on sand, but we must build as if the sand were stone.

Nothing is built on stone; all is built on sand, but we must build as if the sand were stone.

没有什么是建在石头上的;一切都建在沙子上，但我们必须把沙子当作石头来建造。

-- Jorge Luis Borges 豪尔赫·路易斯·博尔赫斯