"I'm a hermit, and this is my fast day, so I couldn't come slowly," said the man sadly. "What is a fast day?" asked Billy. "A day when you don't eat." "Oh!" said Billy, "I thought you meant a day when time flies." "No," said the man, wrapping his legs around and around each other, "no; if that were the case every day would be a fast day, because it's always fly time in this desert." "You seem unhappy. Cheer up!" "I can't cheer up. How is a fellow to cheer when he can't speak above a whisper?" "I mean laugh," said Billy. "Laugh," said the man wearily, "what's that?" "Don't you know what a laugh is?" cried Billy, in surprise. "Why, this is a laugh: ha-ha-ha!" "I don't see any sense in that," said the Hermit; "that's just a noise." "Of course it's a noise. Come, now, I'll tell you a joke: When is a door not a door?" Of course it was very, very old, but so was the Hermit, and Billy wanted to start with the simplest joke he could think of. "Quite impossible." "No; when it's a-jar. Isn't that a good one?" said Billy. "Ha-ha-ha!" "Oh, my! oh, me! what a terrible thing!" cried the man, bursting into tears. "Suppose all the doors should be changed into jars, what would the poor people do?" "But don't you see, that's the joke," said Billy; "a-jar means partly open." "Yes, but if it were still a door how could it be a jar? It's got to be one or the other." "Oh, pshaw!" said Billy, in disgust; "can't you see it's a joke. I think it's very funny." "Oh! is that funny?" asked the Hermit. "Of course." "Then that's the reason it doesn't make me laugh. When I was a boy I broke my humerus and had to have my funny bone extracted, so I can't see anything funny." "Poor fellow!" said Billy sympathetically. "What town is that over there?" "Mirage town," said the Hermit; "but you can't reach it unless you fly." "Why not?" "It's built in the sky." "In the sky? Is it on the road to Bogie Man's house?" "Are you seeking Bogie Man? Oh, me! oh, my! Don't tell me you are seeking him." "But I am," said Billy; "why not?" "Because I've got to hold you if you are, and I'm so tired," said the Hermit, slowly reaching out his arms. "Good-by," cried Billy, giving a jump and bounding out of his reach. "Oh! please come back and tell me another joke, I haven't had a good cry for a week," called the Hermit, holding out his arms. "Too late," Billy called back--"But when is a door not a door? when its a jar." "Thank you," sobbed the Hermit, and the last Billy saw or heard of him he was murmuring, "When is a door a jar," and weeping bitterly. In a twinkling Billy stood at the gates of Mirage Town. Far beneath him he could see the burning hot desert, while through the gates he could see cool, airy houses, beautiful streets shaded by great trees and far beyond soft, green meadows and sparkling brooks.