And though Vetch could not see what Ged saw, when between his strokes he looked ever and again over his shoulder at what lay before the boat's way - though Vetch could not see the dark slopes beneath unmoving stars, yet he began to see with his wizard's eye a darkness that welled up in the hollows of the waves all around the boat, and he saw the billows grow low and sluggish as they were choked with sand.