His hand came upon a place where a tiny stream of water was running down the face of the rock.

'What a stupid I am!' he said to himself.

'I am actually at the end of my journey! And there are the goblins coming back to fetch their things!' he added, as the red glimmer of their torches appeared at the end of the long avenue that led up to the cave.

In a moment he had thrown himself on the floor, and wriggled backwards through the hole.

The floor on the other side was several feet lower, which made it easier to get back.
It was all he could do to lift the largest stone he had taken out of the hole, but he did manage to shove it in again.