"It is never safe to assume I know anything," retorted Christopher naively. "I know such a queer collection of stuff, you see. It's odd, isn't it, the truck that sticks in your memory? If I could only remember things that are worth while as easily as I often do things that aren't I should know quite a lot." "That is the way with all of us, laddie," the old man on the work bench confessed. "I myself would gladly part with a vast deal I have acquired and never yet found a use for." "We ought to have mental rummage sales and bundle out the rubbish we don't need," Christopher remarked. The Scotchman hailed the suggestion with delight. "That would be a capital scheme," acclaimed he. "The only trouble would be to find purchasers for our outgrown ideas." "Oh, somebody would like them," put in Christopher cheerfully. "Mother says there are always people who will buy anything that is cheap no matter what it is." "But my old ideas are not cheap ones," objected the clockmaker. "On the contrary, some of them cost me a great deal in the day of them; they are simply worn out and old-fashioned." "They'd sell--never fear. Mother declares people buy the most impossible truck. A thing is seldom so bad that nobody wants it." "Then that is certainly what we must do with our intellectual junk," was McPhearson's instant answer. "Suppose we advertise a sale of it? I will cheerfully part with 'The Boy Stood on the Burning Deck' which I committed to memory when I was eight years old. I'd sell it outright or would exchange it for one of Shakespeare's sonnets." Christopher greeted the whimsey with a laugh. "Now I," began he, "would sell or swap the water routes from most of our inland cities. We had to learn them when I studied geography and as I have never wanted to ship goods from St. Paul to Philadelphia, for example, I have found no use for them." "You may some day." "I'll risk it. If I did want them I could, perhaps, buy them back," flashed Christopher. "What price would you set upon such possessions?" "You mean the water routes? Well, it cost me a good deal of trouble to memorize them; still, I'd be glad to let them go cheap and be rid of them. I'd trade them for--let me see--an equal number of facts about wireless. With them I'd throw in all my--" he stopped suddenly. "All your what?" "I was going to say all my Latin but changed my mind," the boy replied. "I guess, everything considered, I'd better keep that. It might come in handy sometime. It did the other day." "Oh, I'd keep your Latin, by all means," the Scotchman agreed. A pause, weighted with humorous imaginings, fell between them until Christopher broke out: "Mr. McPhearson!" "Well?" "How would you like to swap some more information about that clock on the Metropolitan Life building for my water routes?" Gravely the clockmaker reflected.