They could see the Picture as well as he could, because it faced them, and in the Picture was the hillside where they were not sitting, all their forms being reproduced in miniature.

And curiously enough, within the scene of the Picture was the scene they were now beholding, so they knew that the Magician was at this moment watching them in the Picture, and also that he saw himself and the room he was in become visible to the people on the hillside.

Therefore he knew very well that they were watching him while he was watching them.
In proof of this, Ugu sprang from his seat and turned a scowling face in their direction; but now he could not see the travelers who were seeking him, although they could still see him.

His actions were so distinct, indeed, that it seemed he was actually before them.

"It is only a ghost," said the Bear King.