Jerry and Peter sat in the moonlight talking it over. Paddy had stopped bringing sticks for his wall. He had dived down out of sight, and he was gone a long time. Suddenly Jerry noticed that the water had grown very, very muddy all around Paddy's new house. He wrinkled his brows trying to think what Paddy could be doing. Presently Paddy came up for air. Then he went down again, and the water grew muddier than ever. This went on for a long time. Every little while Paddy would come up for air and a few minutes of rest. Then down he would go, and the water would grow muddier and muddier.
At last Jerry could stand it no longer. He just had to see what was going on. He slipped into the water and swam over to where the water was muddiest. Just as he got there up came Paddy.
"Hello, Cousin Jerry!" said he. "I was just going to invite you over to see what you think of my house inside. Just follow me."
Paddy dived, and Jerry dived after him. He followed Paddy in at one of the three doorways under water and up a smooth hall right into the biggest, nicest bedroom Jerry had ever seen in all his life. He just gasped in sheer surprise. He couldn't do anything else. He couldn't find his tongue to say a word. Here he was in this splendid great room up above the water, and he had been so sure that there wasn't any room at all! He just didn't know what to make of it.
Paddy's eyes twinkled. "Well," said he, "what do you think of it?"
"I—I—think it is splendid, just perfectly splendid! But I don't understand it at all, Cousin Paddy. I—I—Where is that great pile of mud I helped you build in the middle?" Jerry looked as foolish as he felt when he asked this.
"Why, I've dug it all away. That's what made the water so muddy," replied Paddy.
"But what did you build it for in the first place?" Jerry asked.
"Because I had to have something solid to rest my sticks against while I was building my walls, of course," replied Paddy. When I got the tops fastened together for a roof, they didn't need a support any longer, and then I dug it away to make this room. I couldn't have built such a big room any other way. I see you don't know very much about house-building, Cousin Jerry."
"I—I'm afraid I don't," confessed Jerry sadly.