Duke considered it, trying to keep a firm footing on the shifting quicksand of the other's arguments.

The impression she received, on coming back to this world after a long absence, was of a shifting quicksand.

He needs a higher righteousness than his own; a firmer standing-ground than the shifting quicksand of his own good deeds.

What might he not really have accomplished if the royal support had been anything more solid than a shifting quicksand?

From the shifting quicksand of their speculation we may rise unharmed on the pinions of a faith guided by the principle: "It is written."