Even when they had finished and undressed for the night, they said very little. "Where do our thoughts go when we are asleep?" The Rat inquired casually after he was stretched out in the darkness. "They must go somewhere. Let's send them to find out what to do next." "It's not as still as it was on the Gaisberg. You can hear the city roaring," said Marco drowsily from his dark corner. "We must make a ledge--for ourselves." Sleep made it for them--deep, restful, healthy sleep. If they had been more resentful of their ill luck and lost labor, it would have come less easily and have been less natural. In their talks of strange things they had learned that one great secret of strength and unflagging courage is to know how to "let go"--to cease thinking over an anxiety until the right moment comes. It was their habit to "let go" for hours sometimes, and wander about looking at places and things--galleries, museums, palaces, giving themselves up with boyish pleasure and eagerness to all they saw. Marco was too intimate with the things worth seeing, and The Rat too curious and feverishly wide-awake to allow of their missing much. The Rat's image of the world had grown until it seemed to know no boundaries which could hold its wealth of wonders. He wanted to go on and on and see them all. When Marco opened his eyes in the morning, he found The Rat lying looking at him. Then they both sat up in bed at the same time. "I believe we are both thinking the same thing," Marco said. They frequently discovered that they were thinking the same things. "So do I," answered The Rat. "It shows how tired we were that we didn't think of it last night." "Yes, we are thinking the same thing," said Marco. "We have both remembered what we heard about his shutting himself up alone with his pictures and making people believe he had gone away." "He's in his palace now," The Rat announced. "Do you feel sure of that, too?" asked Marco. "Did you wake up and feel sure of it the first thing?" "Yes," answered The Rat. "As sure as if I'd heard him say it himself." "So did I," said Marco. "That's what our thoughts brought back to us," said The Rat, "when we 'let go' and sent them off last night." He sat up hugging his knees and looking straight before him for some time after this, and Marco did not interrupt his meditations.